Gunfire and explosions rocked a besieged radical mosque in Pakistan's capital Thursday as Islamic militants holed up in the complex snubbed a plea from their captured leader to surrender.

The army seemed to be holding back from a large-scale assault, however. The government was keen to avoid a bloodbath that would further damage President Gen. Pervez Musharraf's embattled administration and said troops would not storm the mosque while women and children were inside.

Interior Minister Aftab Khan Sherpao said soldiers were trying to blast holes in the walls of the fortress-like compound of the mosque and an adjoining seminary for girls, seeking to wear down the defenders' resolve and force a surrender without a bloody battle.

It wasn't clear how many people were holed up in the compound. The Interior Ministry said about 30 die-hard extremists were inside, while intelligence officials said there could be as many as 100. The military said several hundred students also might be in the compound.

Soldiers backed by armored vehicles and helicopters surrounded the Lal Masjid, or Red Mosque, before dawn Wednesday, a day after the start of clashes between security forces and radical followers of the mosque that have killed at least 19 people.

The violence brought to a head a six-month standoff between Pakistan's U.S.-backed government and its top cleric, Maulana Abdul Aziz, who challenged Musharraf with a drive to impose Taliban-style Islamic law in Islamabad.

Journalists were barred from the area around the mosque, but several explosions were heard during a period of intense gunfire before dusk Thursday, sending a plume of black smoke into the sky.

A leader inside the mosque accused troops of firing several mortar rounds that killed 27 female students.

"A large section of the mosque is damaged and fires have broken out in the Jamia Hafsa (seminary)," Abdul Qayyum told The Associated Press by telephone, coughing repeatedly. "It's total chaos here. There is smoke everywhere and a fire in the room where we were keeping dead bodies" from earlier skirmishes.

Sherpao insisted no mortars were fired and said the alleged casualties were "just their claims."

The shooting later eased and the smoke cleared.

Officials said they were using helicopters and explosions in hopes of breaking the nerve of the mosque defenders and inducing a surrender. "We are using restraint on instructions from the president so that people surrender voluntarily," Sherpao said.

Aziz, who was captured Wednesday evening as he tried to slip through the army cordon disguised in a woman's burqa and high heels, said on state television that as many as 700 women and about 250 men remained inside the complex, armed with more than a dozen AK-47 assault rifles.

"If they can get out quietly they should go, or they can surrender if they want to," Aziz said. "I saw after coming out that the siege is very intense. ... Our companions will not be able to stay for long."

His comments raised the prospect of a swift resolution and a victory for Musharraf, who is under growing pressure at home and abroad over spreading religious extremism and his botched attempt to fire Pakistan's chief justice.

But the cleric's brother, Abdul Rashid Ghazi, remained inside the mosque with die-hard followers and rejected the government's call for an unconditional surrender.

Speaking by phone to Pakistan's Geo news channel, Ghazi demanded a guarantee they would not be arrested and said authorities must let him move his mother and sister-in-law out of the complex to safety.

He denied claims by officials that he was using young students as human shields. "The charges against me are forged and fabricated," he said. "The government has been reduced to callousness."

Qayyum, Ghazi's aide, declined to comment on the statement from Aziz or to describe living conditions in the compound, where power and water had been cut off for days.

Deputy Information Minister Tariq Azim said earlier that some of the 1,100 supporters who had fled the mosque and seminary told officials that Ghazi retreated to a cellar along with 20 female "hostages" and that the holdouts had "large quantities of automatic weapons." Officials said the militants also had hand grenades, explosives and homemade gasoline bombs.

Azim said there would be no more negotiations.

"Enough time has already been wasted. It has to be total, unconditional surrender," he said, but added: "As long as there are women and children inside, I don't think that we will go in."

On Thursday, seven men jumped over the mosque wall and tried to escape through a storm drain, but were caught by troops, said Col. Mohammed Ali, a military spokesman. He said the seven were "part of the hard core," but provided no other details.

Since January, the clerics have defied the government by sending students to occupy a library, intimidate shopkeepers selling Western music and films and kidnap alleged prostitutes and police officers as part of a Taliban-style anti-vice campaign.

In his TV interview, the gray-bearded Aziz, still dressed in a burqa, said that his mosque has "a relationship of love and affection with all jihadist organizations" but that it maintains no actual links with such groups.

"We have no militants; we only had students. If somebody came from outside, I have no information on that," he said. He denied responsibility for calls Tuesday from the mosque's loudspeakers for suicide attacks.

Officials said Aziz and Ghazi would be put on trial on more than 25 charges including kidnapping, incitement to murder and arms offenses, while women, children and males not involved in crimes were being granted amnesty.

Students emerging from the mosque Thursday said the morale of those who remained was good, and many stressed that they left only at the insistence of worried parents.

"They are in high spirits," Mehboob Waly said after exiting to meet his waiting father.

Mohammed Naveed, a teenager who responded to his mother's pleas for him to leave, said: "I came out with a heavy heart. I was scared to be inside, but I was also scared to come out."

Like many of the mosque's students, both are from northwestern Pakistan, an impoverished region where radical Islam is strong.