Men who appeared to be Chinese government agents used heavy-handed tactics yesterday to scuttle a press conference that four South Korean lawmakers were holding at a Beijing hotel to discuss the plight of refugees from North Korea.

According to press reports, the hotel function room was plunged into darkness when the lights were shut off moments after the news briefing began. Commands were shouted to clear the room and the security men began shoving journalists into a hallway, the accounts said. The Associated Press reported that one of its photographers was hit in the head during the scuffle.

However, the South Korean delegation and some of the journalists refused to budge. “Please turn on the light, identify yourselves, and explain what you are doing!” said one of the parliamentarians, Kim Moon-soo, according to the Washington Post. “We are members of the National Assembly of the Republic of Korea. If you feel you have reason to stop us, please explain it to us.”

The security agents did not identify themselves and the press conference never resumed.

The lawmakers had just returned from Yanbian, an autonomous region in China that runs along the border with North Korea. Many residents in the area are ethnically Korean.

In an e-mailed statement, the lawmakers demanded an apology and called on China’s communist government to reverse its policy of returning most North Korean migrants to the impoverished police state. “We request China to show leniency toward North Koreans and allow them free passage to a third country of their choice,” the legislators said. They also called on China to release a Korean man serving a five-year prison term for aiding refugees, Choi Young-hoon.

The South Korean Foreign Ministry said it was seeking information about what it termed the “regrettable” incident at the Beijing hotel.

China’s Foreign Ministry had no immediate comment on the episode.

An American specialist on Korea said in an interview that the Chinese were unwise to tangle with the lawmaker who led the delegation, Kim Moonsoo of the Grand National Party.

“This is a universally admired person whose integrity and commitment to democracy is about as strong as anybody in all of Korea,” said Michael Horowitz of the Hudson Institute.

As a pro-democracy activist in South Korea, Mr. Kim spent two years in jail. He is unlikely to retreat in the face of thuggish tactics by security personnel, Mr. Horowitz said. “This is the last guy in the world you want to pick a fight with or make a martyr of,” the scholar said.

Mr. Horowitz said he suspected that the amateurish show of force was a knee-jerk response by low-level officials in the Chinese hierarchy. “We have no idea who ordered this. My supposition was this was not ordered at the highest levels,” he said. “However, now the most senior officials in the Chinese government must respond…. If this is the way the Chinese treat elected legislators of a national party, they’re going to throw into doubt their capacity to conduct an Olympics.”

China has a longstanding alliance with the North Korean regime, but Mr. Horowitz said he believes incidents like the one yesterday highlight the downside for China of backing Pyongyang. “The cost of sustaining Kim Jong Il will become greater and greater and increasingly prohibitive,” the scholar said.

The dust-up in Beijing comes amid a flurry of diplomatic activity in North Korea by American legislators. Rep. Curt Weldon, a Republican of Pennsylvania, is in Pyongyang on a four-day visit. Earlier this week, Rep. Tom Lantos, a Democrat of California, and a strong advocate for human rights, led a delegation that spent three days in North Korea.

The trips are the first visits by American lawmakers to North Korea since May 2003.

In an interview with Radio Free Asia last week, Mr. Weldon said he planned to offer assurances to the North Korean government. “We will let Pyongyang officials know that the U.S. administration has no intention of bringing down the Kim Jong Il regime,” Mr. Weldon said, according to China’s Xinhua news agency.