Bin Laden and senior al-Qaeda members are on the run
"Any country that would knowingly harbour Bin Laden would be out of their minds," US Deputy Defence Secretary Paul Wolfowitz said in response to a question at a Pentagon news briefing.
"They've seen what happened to the Taleban and I think that's probably a pretty good lesson for people not to do that," he added.
Afghan forces in the southern city of Kandahar, meanwhile, said they were intensifying their search for Taleban leader Mullah Mohammed Omar as US warplanes kept up their bombing raids.
The new effort came as American officials admitted they did not know the whereabouts of Osama Bin Laden, suspected of masterminding the 11 September attacks on New York and Washington, or even whether he is dead or alive.
Most of the latest US air strikes targeted former Taleban and al-Qaeda strongholds around Tora Bora, in north-eastern Afghanistan, where Bin Laden had been believed to be hiding last week, and Kandahar in the south, a Pentagon spokesman said.
The newly-appointed Governor of Kandahar, Gul Agha, told the BBC that his forces had arrested up to 80 fighters belonging to Bin Laden's al-Qaeda organisation and that he had sent out search parties to find Mullah Omar.
Haji Gullalai, an intelligence chief in the former Taleban stronghold, said he believed Mullah Omar was sheltering with some 500 men in a mountain redoubt near the village of Baghran, and that ethnic Pashtun forces were preparing to attack.
He said Mullah Omar would be hanged if caught.
Gul Agha said large numbers of Taleban fighters in Kandahar had handed in their weapons.
Search for Bin Laden
US and British special forces are continuing to search the caves of Tora Bora to determine whether al-Qaeda leaders are among 200 bodies found there.
But Pentagon spokesman Rear Admiral John Stufflebeem said on Monday that Bin Laden's location was "anybody's guess".