The Chicago Tribune reported that an offensive was being planned that would involve thousands of American troops and which would go after refuges in Pakistan used by fugitive Osama bin Laden's al- Qaeda network.

"When the winter snows thaw in Afghanistan, the Taliban and al- Qaeda come out (of hiding)," said one official, who asked not to be identified. "It's just prudent to plan to have our forces ready to go after them."

The Pentagon and the US military's Central Command refused to comment on any future military operations.

Another US official told Reuters the planned offensive in Afghanistan would be similar to expanded previous operations in which US Special Operations and other troops supported by warplanes went after guerrillas and transit routes in the Afghan mountains near Pakistan.

The Tribune, in a report from Washington, cited military sources. But the Pakistani government denied to Reuters that it would allow such an operation to extend into its territory.

Such an intervention by some of the 11,000 US troops in Afghanistan would be political dynamite for Pakistani President Gen. Pervez Musharraf, who has allowed only a very limited US military presence in his country. He has cooperated with Washington against al-Qaeda but is under pressure from Islamic parties at home.