B.K. Bangash, Associated Press
Pakistan's former Prime Minister Benazir Bhutto listens to reporters in Islamabad Wednesday. Her supporters' skirmish with police deepened the political crisis.

ISLAMABAD, Pakistan — Supporters of Benazir Bhutto clashed with police in front of parliament Wednesday after she urged party activists into the streets to protest emergency rule, deepening the uncertainty engulfing a Pakistan already shaken by rising Islamic militancy.

Seeking to position herself as the only leader able to unite the country to confront Islamic extremism, the former prime minister toughened her rhetoric against President Gen. Pervez Musharraf, but she left open the possibility of resuming talks if he ends the crackdown.

President Bush, meanwhile, told the U.S.-allied general that Pakistan must go through with parliamentary elections that had been planned for January. Bush commented after a senior U.S. official called Musharraf an "indispensable" ally in the war against extremist groups.

Thousands of Pakistanis have been jailed or put under house arrest since Musharraf assumed emergency powers Saturday, and Bhutto called on her followers to show their defiance of the clampdown on civil liberties.

In an opening skirmish, some 400 loyalists of her Pakistan People's Party, the country's largest, marched up to riot police blocking their way to the parliament building, where lawmakers minutes earlier had rubber-stamped the emergency declaration.

Police fired tear gas over their heads and beat and arrested a few who broke through barricades topped with barbed-wire, including several women.

Naheed Khan, a close aide to Bhutto, waded into the brief melee. She whacked a policeman on the shoulder and screamed: "Who are you? How dare you take action against women?"

The demonstrators pulled back through the choking gas, chanting "Benazir! Benazir!" and "Down with the emergency!"

Musharraf, who has been promising to restore democracy since seizing power in a 1999 coup, has ousted independent-minded judges, put a stranglehold on the media and granted sweeping powers to authorities to crush dissent since declaring emergency rule.

The general says he suspended the constitution because the courts were hampering his efforts against extremist groups, such as by ordering the release of suspects held without charge. Political opponents, however, contend the crackdown is really meant to protect Musharraf's hold on power.

Three days of protests by lawyers — angered by the attacks on the judiciary — were quickly put down. Police in the southern city of Karachi were trying to arrest eight lawyers on treason charges for distributing anti-Musharraf leaflets. Conviction could bring death sentences.

Bhutto's decision to join in protests added a new dimension to worsening political instability that has seen anger at military rule spread and Islamic militants allied with the Taliban and al-Qaida strengthen their hold on areas along the border with Afghanistan.

With the encouragement of the United States, Musharraf had been negotiating with Bhutto on forming an anti-militant political alliance and sharing power after parliamentary elections.

The talks yielded an amnesty that dropped corruption charges against Bhutto, paving the way for her return last month following eight years in self-imposed exile. Her jubilant Oct. 18 homecoming was shattered by a suicide bombing that killed more than 140 people.

But with the elections on hold, Bhutto has pulled back from negotiations, and she urged her supporters to defy Musharraf's ban on demonstrations by marching on parliament and attending a mass rally called for the nearby city of Rawalpindi on Friday.

Bhutto urged her supporters to try to reach Rawalpindi "at all costs." She said it was important to stand against Musharraf, saying his authoritarian ways have fueled extremism and destabilized the country of 160 million people.

"We are talking about the future of Pakistan as a modern nation," she said at a news conference. "We are talking about its impact on the region — if a nuclear-armed country like Pakistan implodes."

Rawalpindi's mayor said police would be out in force to prevent anyone reaching the park where Bhutto hoped to address supporters Friday.

"We will ensure that they don't violate the ban on rallies, and if they do it, the government will take action according to the law," Mayor Javed Akhlas told The Associated Press.

Akhlas said there was a "strong threat" of another suicide attack against Bhutto.

Bhutto said she would take the risk, and renewed her charge that elements in the government and security forces were in cahoots with Islamic extremists trying to kill her. Militants were widely blamed for last month's failed attempt on her life.

She said religious militants feared her as "the only leader in Pakistan who has a national base who can confront them. They are quite happy with anybody else." She didn't elaborate.

Saying more than 400 members of her party were arrested Wednesday, Bhutto said she had not negotiated with Musharraf since he resorted to strong-arm tactics over the weekend. But she said talks could resume if he yielded to growing domestic and international pressure to end emergency rule.

"If Gen. Musharraf wants to kick start the negotiations for a peaceful transition, then he must revive the constitution, retire as chief of the army staff by Nov. 15 and hold the election as scheduled," Bhutto said.

She said her party would stage a "long march" over the 200 miles from Lahore to Islamabad on Tuesday unless Musharraf agreed to her conditions.

The United States and other foreign donors to Pakistan are pressing for the elections to be held on time and for an end to the emergency decree. They are also urging Musharraf to keep a promise to quit his powerful army post.

Pakistani ministers have suggested the election could be postponed for up to a year. However, the head of the ruling party expressed optimism Wednesday that the vote could be held as scheduled.

The American president said he had "a very frank discussion" with Musharraf on Wednesday insisting on the need for elections and for the leader to give up his army command.

"My message was that we believe strongly in elections, and that you ought to have elections soon, and you need to take off your uniform," Bush said.

Despite its criticism of Musharraf's crackdown, the U.S. government's public comments have been mild, reflecting concerns about angering a key ally in confronting Islamic extremists in South Asia.

Before Bush spoke to reporters, Deputy Secretary of State John Negroponte repeated U.S. criticism of Musharraf's crackdown, but described the Pakistani leader as a key ally.

Musharraf "has been indispensable in the global war on terror, so indispensable that extremists and radicals have tried to assassinate him multiple times," Negroponte said. "The bottom line is, there's no question that we Americans have a stake in Pakistan."

Associated Press writers Munir Ahmad, Zarar Khan and Sadaqat Jan in Islamabad and Ashraf Khan in Karachi contributed to this report.