YANGON — Soldiers clubbed and dragged away activists while firing tear gas and warning shots to break up demonstrations today before they could grow, and the government cut Internet access, raising fears that a deadly crackdown was set to intensify.

Troops also occupied Buddhist monasteries in a bid to clear the streets of Burma’s revered monks, who have spearheaded the demonstrations.

The government said 10 people have been killed since the violence began earlier this week, but Prime Minister Brown of Britain said he believed the loss of life in Burma was “far greater” than is being reported. Dissident groups have put the number as high as 200, although that number could not be verified.

Witnesses said security forces aggressively broke up a rally of about 2,000 people near the Sule Pagoda in the largest city, Yangon. About 20 trucks packed with soldiers arrived and announced over loudspeakers, “We give you 10 minutes to move out from the road. Otherwise we will fire.”

A group of about 10 people broke away from the main crowd and rushed toward a line of soldiers, who were dressed in green uniforms with red bandanas around their necks, holding shields, and automatic weapons. The people were beaten up, and five were seen being hauled away in a truck.

Soldiers dispersed the other protesters, beating them with clubs and firing shots in the air.

“People in this country are gentle and calm. (But) people are very angry now and they dare to do anything,” a shopkeeper, who witnessed the clash and did not want to be named for fear of reprisal, said

Elsewhere, riot police played cat-and-mouse with smaller groups of die-hard activists, sometimes shooting into the air.

The clash near the Sule Pagoda was the most serious of the several sporadic — though smaller — protests that were reported. Earlier today, soldiers and riot police dispersed a crowd of 300, sealing the surrounding neighborhood and ordering them to disperse. Elsewhere, they fired warning shots to scatter a group of 200.

By sealing monasteries, the government seemed intent on clearing the streets of the cinnamon-robed monks. This could embolden troops to crack down harder on remaining civilian protesters.

Efforts to squelch the demonstrations appeared to be working. Daily protests drawing tens of thousands of people had grown into the stiffest challenge to the ruling military junta in two decades, a crisis that began August 19 with rallies against a fuel price increase, then escalated dramatically when monks joined in.

“Now there are no monks, we have no one to turn to,” a young woman who took part in yesterday’s protest with her boyfriend, said. He failed to turn up for dinner today, she said, and now she fears he may have been detained.

Security forces first moved against the anti-government protesters on Wednesday, when the first of the 10 deaths was reported. Images of bloodied protesters and fleeing crowds have riveted world attention on the escalating crisis, prompting many governments to urge the junta in Burma to end the violence.

But by Burmese standards, the crackdown has so far been muted, in part because the regime knows that killing monks could trigger a maelstrom of fury.

America imposed new sanctions on the junta’s leaders, and the United Nations dispatched a special envoy, who is expected to arrive tomorrow.

“Clearly the government of Burma, the regime there, is facing a population that does not want to suffer quietly under its rule anymore,” a State Department spokesman, Tom Casey, said.

Australia’s ambassador to Burma, Bob Davis, said he had heard unconfirmed reports that “several multiples of the 10 acknowledged by the authorities” may have been killed by troops in Yangon. Scores have been arrested, carted away in trucks at night or pummeled with batons in recent days, witnesses and diplomats said, with the junta ignoring all international appeals for restraint.

Following telephone talks with President Bush and Prime Minister Wen of China, Mr. Brown said “we believe the loss of life is far greater than is being reported so far.”

Mr. Brown’s Office refused to give an estimate, saying British diplomats could only guess at how many people had been killed because they were unsure what was happening outside Yangon.

The Washington-based dissident group, U.S. Campaign for Burma, said about 200 protesters were killed and scores more arrested and beaten. The bloodiest day was yesterday, when troops opened fire into a crowd.

“The military was out in force before they even gathered and moved quickly as small groups appeared breaking them up with gunfire, tear gas and clubs,” the top American diplomat in Burma, Shari Villarosa, said.

“It’s tragic. These were peaceful demonstrators, very well behaved.”

Ambassador Mark Canning of Britain told BBC-TV that “there have been a lot of arrests,” with up to 50 people detained at one time.

Getting accurate casualty figures has been difficult, with residents too afraid to speak out and journalists barred from openly entering the country. Soldiers and police were going door-to-door in some hotels looking for foreigners.

The American Embassy in Yangon urged any Americans still in Burma to avoid any demonstrations or marches, refrain from photographing any troops, and avoid traveling after a nighttime curfew takes effect.

Video emerged of a striking image — the shooting death yesterday of a man identified as Japanese journalist Kenji Nagai of the video agency APF News.

The Democratic Voice of Burma released video of security forces opening fire on protesters, including a man falling forward after apparently being shot at point-blank range, and the opposition shortwave radio station based in Norway said the victim was Nagai, 50.

Another image posted on the Web site of Japanese TV network Fuji showed Nagai lying in the street, camera still in hand, with a soldier pointing his rifle down at him.

Reporters Without Borders and the Burma Media Association condemned new attempts by the military rulers to exert pressure on foreign journalists and the domestic media. The groups said security forces raided several Yangon hotels yesterday to check the IDs of foreign journalists.

The junta ordered the closure of several privately owned newspapers that refused to print government propaganda, the groups said.

The Association of Southeast Asian Nations expressed “revulsion” at the violence in Burma and told the junta “to exercise utmost restraint and seek a political solution.” Demonstrations against the junta were seen in Malaysia, Thailand, Japan, and elsewhere.

Southeast Asian envoys were told by Burmese authorities today that a no-go zone had been declared around five key Buddhist monasteries, one diplomat said, raising fears of a repeat of 1988, when troops gunned down thousands of peaceful demonstrators and imprisoned the survivors.

Gates were locked and key intersections near monasteries in Yangon and the second-largest city of Mandalay were sealed off with barbed wire, and there was no sign of monks in the streets.

“We were told security forces had the monks under control” and will now turn their attention to civilian protesters, the Asian diplomat said on condition of anonymity, citing protocol.

The government suspended the services of the two Internet service providers, BaganNet and Myanmar Post and Telecom, but big companies and embassies hooked up to the Web by satellite remained online. The Internet has played a crucial role in getting news and images of the pro-democracy protests to the outside world in the past month.

Yesterday was the most violent day in more than a month of protests — which at their height have brought an estimated 70,000 demonstrators to the streets. Bloody sandals lay scattered on some streets as protesters fled shouting “Give us freedom, give us freedom!”

Truckloads of troops in riot gear raided Buddhist monasteries on the outskirts of Yangon, beating and arresting dozens of monks, witnesses and Western diplomats said.

“I really hate the government. They arrest the monks while they are sleeping,” a 30-year-old service worker who saw some of the confrontations from his workplace said. “These monks haven’t done anything except meditating and praying and helping people.”

The American special envoy to Burma, Ibrahim Gambari, headed to the country to promote a political solution and could arrive as early as tomorrow, one Western diplomat said on condition of anonymity.

Though some analysts said negotiations were unlikely, the diplomat said the decision to let Mr. Gambari in “means they may see a role for him and the United Nations in mediating dialogue with the opposition and its leaders.”

China, Burma’s largest trading partner, for months quietly counseled the regime to speed up long-stalled political reforms. Some analysts say Beijing would hate to be viewed as party to a bloodbath as it prepares for the 2008 Olympics.

“China hopes that all parties in Myanmar exercise restraint and properly handle the current issue so as to ensure the situation there does not escalate and get complicated,” a Chinese Foreign Ministry spokeswoman, Jiang Yu, said in Beijing.

But every other time the regime has been challenged, it has responded with force.

“Judging from the nature and habit of the Myanmar military, they will not allow the monks or activists to topple them,” a Burmese scholar at Chulalongkorn University in Bangkok, Chaiyachoke Julsiriwong, said.