KABUL/WASHINGTON - Northern Alliance troops and tanks launched an attack on the besieged Afghan city of Kunduz on Thursday after attempts to negotiate a Taliban surrender collapsed.

As Alliance artillery shelled enemy positions in and around the Taliban's last enclave in northern Afghanistan, U.S. warplanes bombed the Taliban from the air in the 47th day of America's campaign against Osama bin Laden's embattled protectors.

U.S. surveillance planes -- bolstered by the addition of the sophisticated high-flying Global Hawk -- patrolled the Afghan skies in a relentless hunt for the fugitive Islamic militant, believed to hiding in the mountains of southern Afghanistan.

The Northern Alliance said its forces were closing in on Kunduz and vowed to swiftly capture the city where thousands of Taliban fighters, as well as Pakistanis, Arabs and Chechens allied with bin Laden, are encircled.

The offensive followed contradictory reports of a surrender agreement, but the Alliance said it had tried and failed to negotiate a surrender with its foes and was forced to attack.

"We have tried to settle the issue of Kunduz through negotiation but we have been forced to choose a military solution," Alliance Interior Minister Yunus Qanuni told Reuters in an interview in Kabul. "At the moment our forces are advancing. We hope by tomorrow we will have secured Kunduz."

He said 15,000 Taliban troops in Kunduz, including up to 10,000 foreigners, "had no intention of surrendering" despite stop-and-start negotiations that had dragged on for days.

The United States has made plain it has little pity for the besieged pro-Taliban forces, particularly the Arab and other foreign fighters, and has opposed any deal to allow them to escape being captured or killed.

U.S. Defense Secretary Donald Rumsfeld said on Wednesday, "Any idea that those people should be let loose on any basis at all to leave that country to go bring terror to other countries and destabilize other countries, is unacceptable."

Washington believes at least some of the foreigners are members of the al Qaeda network headed by bin Laden, which is accused of carrying out the Sept. 11 attacks on the United States that killed about 4,000 people.

The Northern Alliance said the Afghan Taliban in Kunduz were willing to surrender, but the al Qaeda fighters, expecting no mercy if they gave up, were fighting to the death and executing would-be deserters.

The failed surrender negotiations were apparently intended to avert a possible massacre of the trapped foreign fighters, who are loathed by the Northern Alliance.

The fears of a massacre were underlined by an announcement by the International Committee of the Red Cross, which said in Geneva that 400 to 600 bodies had been found in Mazar-i-Sharif, a strategic northern city recently captured by the Alliance.

The Red Cross said it could not say whether the dead had been executed or killed in fighting. Nor was it able to say whether they were Afghans or foreigners.

If Kunduz falls, the Taliban would be left with control of only their so-called spiritual home around Kandahar, for a final fight against the U.S.-backed forces.

The Taliban were also completely isolated diplomatically on Thursday when Pakistan ordered it to close its embassy in Islamabad, the hard-line Islamic militia's last remaining diplomatic mission anywhere in the world.

The Taliban complained the move was dictated by the United States.

"The pressure is clear," Taliban ambassador Mullah Abdul Salam Zaeef told Qatar's al-Jazeera television station. "At first the pressure was to close the consulate in Karachi and two days ago they closed the consulate in Peshawar. All this was the result of American pressure."

In the United States, Americans celebrated their Thanksgiving holiday and President George W. Bush signaled there would be no letup in war on terrorism.

Bush spent the holiday at Camp David, the presidential retreat in Maryland, surrounded by family but also consulting with his national security and military advisers.

On Wednesday, Bush paid special tribute to the U.S. military's contribution since the Afghan campaign began on Oct. 7. "We've made a good start," he told troops at Fort Campbell, Kentucky. "Thanks to you, every nation is seeing what will happen if you cash in your lot with the terrorists. Thanks to you, there is less fear in the world, and more freedom, and more hope, and a better chance for peace."

As U.S. special forces scoured the mountains where bin Laden and other al Qaeda members might be hiding, the military added the formidable Global Hawk to its high-tech surveillance effort. The U.S. Air Force has four of the planes, which provide high-resolution, real-time imagery of large areas.

The skies above Afghanistan are also patrolled by unmanned Predator drones, capable of firing Hellfire anti-tank missiles at tunnels and caves where bin Laden is suspected of hiding.

Among an array of cutting-edge technology being used by U.S. special forces are sensors capable of homing in on heat sources in the cold Afghan mountains. They can penetrate darkness and solid rock to detect vibrations and magnetic fields that may provide clues to bin Laden's hiding place.

Apart from the military action, the U.S. war on terrorism is being aggressively waged by its intelligence services. The Washington Post reported on Thursday that about 360 suspects with alleged connections to al Qaeda had been arrested and detained in 50 countries at the urging of the CIA.

The Post said the massive international roundup mirrored a broader detention program by the FBI in the United States that has netted more than 1,100 people, some of whom are believed to have information about terrorists.

The numbers of arrests were much larger than those previously reported and the newspaper quoted sources as saying they may have thrown some al Qaeda cells off balance, although it was not clear whether any attacks had been prevented.

With the Taliban under siege in both Kunduz and Kandahar, two more Western allies said on Thursday they were prepared to commit troops to the U.S.-led Afghan campaign.

France plans to commit 5,000 troops, including nearly 2,500 naval and air force personnel with the deployment in the Indian Ocean of the nuclear-powered aircraft carrier Charles de Gaulle. French President Jacques Chirac said this week that about 2,000 troops were already involved in the campaign.

Poland said it would deploy a contingent of some 300 soldiers, including chemical and biological weapons experts and 80 crack troops from its GROM ("Thunder") special forces. The Polish troops will not be ready until January.

Germany prepared to host U.N.-sponsored talks next week in Bonn on the future of Afghanistan, and the Northern Alliance's Qanuni said Afghan groups would elect a leadership council, or shura, to oversee the transfer of power to a broad-based government and sketch out the framework for future rule.

The U.N. deputy representative for Afghanistan, Francesc Vendrell, said on Thursday the meeting was "a good start" but the Afghan groups would have to overcome years of conflict and mistrust to agree on the shape of an interim government.

"I don't think we should have too high expectations that they are going to meet and immediately agree to the kind of plan we put forward at the (U.N.) Security Council," Vendrell said after talks with British Foreign Secretary Jack Straw. Nampa-Reuters