The Taliban has accused US forces of killing more than 100 people in a hospital in the western Afghanistan city of Herat, and of using chemical and biological weapons in its campaign.
The charges came as aid agencies warned of thousands of refugees fleeing bombs and famine making their way towards the border with Pakistan.
The Taliban ambassador to Pakistan, Mr Abdul Salem Zaeef, said a 100-bed hospital in Herat was bombed by US and British planes, killing all the patients, doctors and nurses present.
"It is now clear that American planes are intentionally targeting the Afghan people," he said.
"The goal is to punish the Afghan people for having chosen an Islamic system."
The US Defence Secretary, Mr Donald Rumsfeld, said there was no evidence that US warplanes had bombed the hospital. "We have absolutely no evidence at all that would suggest that that allegation . . . is correct. I'm sure it's not," he said.
Mr Rumsfeld also gave no assurances that US bombing of Afghanistan would stop during the Muslim fasting month of Ramadan which starts mid-November. The Pakistani President, Mr Pervez Musharraf, had said earlier yesterday: "One would hope and wish that this campaign comes to an end before the month of Ramadan."
The Pakistan Foreign Ministry said it was not going to open the border to allow more refugees in because it was not ready to cope with an influx.
The Taliban leader, Mr Mullah Mohammad Omar, in a statement from an unidentified location near Kandahar, expressed his condolences for those killed in US-led air raids or during anti-American protests around the world.
While the Afghan capital, Kabul, remained quiet yesterday, the US began bombing the city early today. Two US jets struck Taliban positions north of the city yesterday afternoon. The Taliban positions are blocking an advance of Northern Alliance forces poised north of the capital.
The charges that Washington had used chemical and biological weapons came from a Taliban Information Ministry official, Mr Abdul Hanan Himat.
"Today in my contact with doctors in Herat and Kandahar, they told me that they have found signs that Americans are using biological and chemical weapons in their attacks," he said.
The Taliban also claimed they had found pieces of a US aircraft near Kandahar and a wrecked helicopter in nearby Helmand province, apparently from the US commando raid on Saturday that publicly started the land campaign.
The US has denied any loss in the weekend mission other than a helicopter that crashed in Pakistan, killing two US soldiers. The Taliban said civilian Afghan casualties continued, reaching 1,000. Witnesses have seen several dozen dead and wounded in Kabul. The US says it has complete air supremacy and has destroyed most anti-aircraft guns.
Meanwhile, in Pakistan police detained workers of the main Islamic party, and stopped its leader from entering Sindh province on the eve of a planned protest in Jacobabad, where US forces are using the airport. The Jamaat-e-Islami leader, Mr Qazi Hussain Ahmed, was arrested as part of a crackdown on protest.