The opposition Northern Alliance said early Tuesday it had given the Taliban three days to lay down their weapons or face an all-out assault on Kunduz, the beleaguered militia's last northern stronghold.

"If there is a fight in Kunduz, it will be a bloody one because there are 3,000 foreign fighters and they have nowhere to go," alliance spokesman Attiq Ullah said from the northern city of Mazar-e-Sharif.

Meanwhile, international negotiators reportedly agreed to meet this weekend in Germany to discuss forming a new broad-based Afghan government, and more U.S. commandos joined the hunt for Al Qaeda leader Usama bin Laden and other terrorist suspects in southern Afghanistan. 

Near Kunduz Monday, bombardment by U.S. warplanes moved closer to the encircled city, and Northern Alliance artillery joined in what appeared to be the heaviest attacks at the front in days.

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Alliance commanders continued to seek a surrender, using two-way radios to negotiate. But refugees who reached alliance lines recounted a defiant message from the foreign fighters in the city: "We are going to be martyrs. We are not leaving Kunduz."

Refugees said the foreigners — mostly Arabs, Pakistanis and Chechens — were preventing Afghan Taliban fighters from surrendering. Refugees have reported that several hundred would-be Taliban defectors were shot by their own side.

Refugee Ahmed Wahid said the foreigners and hard-core Taliban in Kunduz had smeared their vehicles with mud to avoid detection by U.S. jets and were sleeping in relief agency offices to escape bombs.

Apparently readying for an attack on Kunduz, alliance tanks fired from ridges that had been held by the Taliban just a day earlier. Alliance soldiers moved into what had been a no-man's land in a valley near the city.

At the Pentagon, Defense Secretary Donald H. Rumsfeld described fighting around Kunduz as fierce. He said he had seen reports of Taliban fighters killed to prevent their surrender but could not confirm them.

Opposition Agrees to U.N.-Brokered Talks on Neutral Ground 

Working on the critical issue of stabilizing the tribally fractured country, negotiators reported progress in persuading Afghanistan's major ethnic groups to work together on forming a government. No date or place for talks has been announced, but a Pakistani diplomatic source, speaking on condition of anonymity, said a meeting would begin Saturday, possibly in Berlin.

The United Nations said in New York that the victorious Northern Alliance has not yet formally accepted Secretary-General Kofi Annan's invitation to an all-parties conference. However, alliance leaders have assured U.S. officials they will take part.

"There is really a hunger for peace," James F. Dobbins, the U.S. envoy to the alliance, said in Pakistan after meeting its leaders near the Afghan capital of Kabul.

"There's a willingness to compromise," he told reporters. "There's a recognition that the international situation is transformed."

Alliance leaders asked the United Nations to find representatives from the Pashtuns, the ethnic group most closely linked to the Taliban, to attend the talks. The alliance consists mainly of ethnic Tajiks, Uzbeks and Hazaras; the Pashtuns, the largest ethnic group, may not accept a new government unless they play a major role.

Dobbins said he was convinced the movement was committed to giving the Pashtuns a role.

Taliban Retains Tenuous Grip on Kandahar 

Backed by U.S. bombardment, the Northern Alliance swept the Taliban out of northern Afghanistan last week and seized Kabul. The Taliban hold also fell apart in the south, where local leaders took control of many areas, but the militia held onto the southern city of Kandahar, their home base. 

Rumsfeld said the Taliban were under increasing pressure to release their grip on the city.

"It is apparently at the moment still a standoff," he said of Kandahar. "There are southern tribes that are applying pressure and engaged in discussions [with the Taliban], and there's firing and the U.S., coalition forces, are providing some air support."

Rumsfeld said the United States would not let Taliban leader Mullah Mohammed Omar escape from Kandahar, even if opposition leaders negotiated a deal for him to depart.

In other developments:

— In Jalalabad, the new anti-Taliban governor of Nangarhar province, Abdul Kadeer, offered to help U.S. and British commandos search for bin Laden and Al Qaeda fighters in the rugged mountains of his province. He said there were hundreds of Arab fighters holed up in the Tora-Bora camp in Nangarhar and he would be happy to help coalition forces root them out.

— In Kabul, where most forms of entertainment were banned during strict Taliban rule, television aired news, cartoons and three hours of readings from the Quran, Islam's holy book. The programs were introduced by Mariam Shekeba, whose broadcast career had been interrupted for five years because the Taliban barred women from showing their faces in public.

— About 60 French foreign legion troops were at the Khanabad air base in Uzbekistan, preparing to head to Mazar-e-Sharif. Commander Herve Fouilland said the French were working with Americans and Jordanians on a plan for restoring Mazar-e-Sharif's airstrip so aid supplies could be flown in.

The Associated Press contributed to this report