Taleban officials say U.S. jets carried out more daylight air strikes against targets in the southern Afghan city, Kandahar.
The strikes come as officials in Islamabad have confirmed the presence of U.S. military personnel at bases in Pakistan.
Reports from the Kandahar region say large numbers of people are fleeing their homes. The strikes, which began late Wednesday across Afghanistan, were the heaviest yet of the four-day air campaign against terrorist-related targets in Afghanistan.
A spokesman for the opposition Northern Alliance says alliance fighters have taken the key town, Chaghcharan, the capital of Afghanistan's Gur Province. The province borders eight others in Afghanistan, four of which are considered strategic to controlling the country.
Pakistani newspapers report the presence of U.S. military personnel at several bases in the southern and western parts of the country.
Pakistani officials say the presence of U.S. troops using Pakistani bases does not mean U.S. combat troops have landed in Pakistan, but only that Pakistan is honoring its pledge to provide "logistical" support to the effort to fight terrorism.
Meanwhile, Pakistani officials are warning they will not tolerate violent opposition to their policy of supporting the coalition partners carrying out strikes against targets in Afghanistan. Pakistan Foreign Ministry spokesman Aziz Khan says any Afghan refugees who engage in violence will be sent back across the border.
"The refugees are given shelter in the country because they are refugees," he said. "They should confine themselves to being refugees and not start having political agitations and things of that nature. Anyone who indulges in such activities should be sent back."
Abdul Ghani Ansari, a leader of the religious-based JUI party, has called for Friday protests against the presence of U.S. troops on Pakistani soil.
Pakistan's president, General Pervez Musharraf, who marks the second anniversary of the coup that brought him to power Friday, has warned extremist activity from any quarter will not be tolerated in Pakistan. He says he will take stern action against activities aimed at harming Pakistan's national interests.