ISLAMABAD — President Musharraf announced today that Pakistan would hold parliamentary elections by mid-February, a move praised by America, which has been pressuring its ally to restore democracy.

General Musharraf’s government had said in the wake of Saturday’s declaration of emergency rule that the vote could be delayed by as long as a year.

But with anger over military rule spreading, America and domestic opponents have been stepping up pressure on General Musharraf to end the emergency rule. President Bush personally urged General Musharraf yesterday to hold the elections as planned and leave his military post.

State-run television flashed General Musharraf’s announcement that the elections would proceed just a month later than originally planned. The news was seen as an indication that the emergency would be short-lived because authorities would likely have to ease up on security restrictions to allow campaigning.

“We think it is a good thing that President Musharraf has clarified the election date for the Pakistani people,” a White House spokeswoman, Dana Perino, said.

General Musharraf’s decision, announced after a meeting of his National Security Council, was denounced by opposition leader Benazir Bhutto, who called it insufficient and said he should step down as army chief within a week.

A Bhutto spokesman said authorities arrested hundreds of her supporters overnight to head off a major rally she is planning near Islamabad on Friday.

Attorney General Malik Mohammed Qayyum forecast that the state of emergency would be lifted in “one or two” months.

“It depends on how the law and order situation improves,” Mr. Qayyum said.

General Musharraf, who seized power in a 1999 coup, maintains that restoring democracy is his ultimate aim and the emergency was needed to prevent political instability, protect economic growth, and maintain the campaign against extremism and terrorism.

Pakistan, a country of 160 million, has been wracked by Taliban and Al Qaeda-linked violence, including suicide bombings and clashes in its troubled northwest, where the insurgents have in recent weeks scored a series of victories against government forces.

Critics say General Musharraf imposed the emergency measures to maintain his own grip on power by subverting the Supreme Court, which is set to rule on the legality of General Musharraf’s recent re-election as president.

Days of protests, most of them by lawyers angered by the attacks on the judiciary, have been quickly and sometimes brutally put down, and thousands of lawyers and opposition activists have been detained.

Four of those arrested were charged with treason today for making anti-Musharraf speeches in the southern port city of Karachi. The men — three politicians from small leftist political parties and a labor union activist — were the first government opponents charged with treason since the emergency was imposed. If convicted, the charge carries a maximum penalty of death.

Police in Karachi also were trying to arrest eight lawyers on treason charges for distributing anti-Musharraf leaflets.

In Islamabad, police chased about 20 high-school students into the city’s bar association headquarters after they showed up in solidarity with dozens of protesting lawyers, who were observing the fourth day of a nationwide strike.

In Lahore, in eastern Pakistan, more than 100 professors boycotted classes and marched on the campus of the state-run University of the Punjab.

Perhaps more troubling for General Musharraf, however, has been Ms. Bhutto’s move to join the protests, adding a new dimension to the worsening political instability.

Authorities appeared determined to prevent a large protest called by her for Friday in Rawalpindi, a garrison city on the outskirts of Islamabad. About 20 policemen were posted today to keep people out of the park where rally was to be held, Liaquat Bagh — named for Pakistan’s first prime minister, who was assassinated there in 1951.

The city’s police chief warned that suicide bombers were preparing to attack the rally.

“We have intelligence reports that suicide bombers have entered Rawalpindi,” police chief Saud Aziz said. He added that the warning was based on specific information and “the situation is very serious.”

Mr. Bhutto’s own jubilant homecoming procession last month following eight years in exile was shattered by suicide bombers, leaving more than 145 people dead. Authorities suspect Islamic militants in that attack.

With Ms. Bhutto showing no signs of calling off the rally — she has repeatedly said she is willing to risk more bombings — police arrested at least 800 of her supporters across the eastern province of Punjab overnight, a spokesman for the opposition leader, Jamil Soomro, said.

But the government denied the arrests, saying no such crackdown had been ordered.

“According to my information, only four members from her party were detained last night when they defied a ban on rallies,” a spokesman for the Interior Ministry, Javed Iqbal Cheema, said.

For days, the White House has faced questions about why Mr. Bush was not taking a tougher line against General Musharraf who since Saturday’s emergency declaration has ousted independent-minded judges, put a stranglehold on the media and arrested thousands of mainly moderate, secular Pakistanis.

Mr. Bush, personally stepping into the political crisis for the first time, said he told General Musharraf in a 20-minute conversation: “You can’t be the president and the head of the military at the same time.

“My message was very plain, very easy to understand, and that is, the United States wants you to have the elections as scheduled and take your uniform off,” Mr. Bush said.

A Pakistani Foreign Ministry statement said General Musharraf, a key American ally in its war on terrorism, had told Mr. Bush he “was committed to full democracy and civilian rule in the country as he had promised to the people of Pakistan.”