KABUL/WASHINGTON, 7 November — The Taleban yesterday claimed they downed a US helicopter killing four servicemen. The militia paraded what they said were parts of the downed US chopper through the streets of Kabul in a show of defiance on the 31st day of Washington’s air assault. The Taleban had a few days back also claimed shooting down a US helicopter.

Officials in Pakistan confirmed a helicopter crashed in Pakistan early Monday after taking fire from the Taleban but would not comment on casualties. The vice-chairman of the Pentagon’s Joint Chiefs of Staff categorically denied claims that Taleban forces shot down US helicopter killing four US soldiers on board.

Kabul residents said a group of armed Taleban soldiers drove through the city with what appeared to be the control panel of a military helicopter on display in their four-wheel-drive vehicle.

Later they stopped on a main road and announced to the public that the wreckage was from a US helicopter shot down by Taleban troops.

"Their attack here will soon share the fate of this aircraft," a Taleban fighter shouted through a loudspeaker as the wreckage was driven through Kabul.

Abdul Henan Hemat, chief of the Taleban’s official Bakhter news agency, told AFP that the helicopter had been hit on Monday during a mission over Afghanistan but it managed to make it across the border before crashing. Pakistani officials said the helicopter crashed in Chaghi district, near the Afghan border and the Dalbandin air base in Balochistan. "It took fire in Afghanistan and it managed to enter into Pakistan where it crashed. The Americans tried to remove the debris," a senior Balochistan provincial official said, requesting anonymity.

A US Embassy spokesman in Pakistan said he could not confirm or deny that a helicopter had crashed on Sunday night or Monday.

Meanwhile, US warplanes attacked Taleban guns bearing down on an opposition-held airfield north of the capital and the opposition claimed a battlefield victory near the northern city of Mazar-e-Sharif.

Opposition forces claimed a major victory as US President George W. Bush warned that the regime’s ally Osama Bin Laden was seeking nuclear weapons and was a threat to civilization. The opposition claim was impossible to confirm independently, but a Taleban spokesman said there was heavy fighting south of the key city of Mazar-e-Sharif and US bombers were in action over the north of the country.

According to a senior US military official, US forces have used the largest bomb in its inventory — a 15,000-pound (6,804-kg) "daisy cutter" — against Taleban forces in Afghanistan twice in the past week. The BLU-82 bomb is so big it is loaded on a pallet and pushed out of the back of a C-130 transport plane, said Gen. Peter Pace, vice chairman of the Joint Chiefs of Staff. The bomb floats to the ground on a parachute and is detonated three feet off the ground by a probe sticking out the bottom. "They make a heck of a bang when they go off and the intent is to kill people," said Pace. He said the bomb, which was originally designed to clear helicopter landing zones in the Vietnam War, is most effective against troops in light defensive positions, he said. A loud explosion also rocked Kabul yesterday evening, minutes after residents reported hearing a helicopter flying over the city.

Muhammad Ashraf Nadeem, spokesman for opposition commander Atta Muhammad, told AFP via satellite phone from near the front lines that three districts to the south of Mazar-e-Sharif had fallen in heavy fighting.

He said Zari, Keshendeh and Aq-Kupruk were all in the hands of the opposition Northern Alliance after days of heavy fighting and intense US airstrikes. A Taleban minister criticized Afghanistan’s neighbors for letting the US use bases in their countries.

Amir Khan Muttaqi, the education minister and main Taleban spokesman, said Tajikistan and other neighbors would face "Islamic and national" pressure to stop American forces using the bases.

"They should not cooperate with them," Muttaqi told AFP in a statement on the US bases in the central Asian states of Tajikistan and Uzbekistan to the north of Afghanistan.

Yesterday, as Germany announced it was ready to send 3,900 military personnel to join the campaign, Bush spoke to stiffen the sinews of the alliance as a coalition ground assault appeared closer.

Earlier, Bush’s Defense Secretary Donald Rumsfeld, returning from Afghanistan’s neighbors after seeking greater military cooperation, said US special forces on the ground had been reinforced, and would grow further.