In an interview conducted inside Afghanistan this week with Pakistan's respected Dawnnewspaper, Osama bin Laden has claimed he has nuclear and chemical weapons and may use them in response to US attacks.
The White House said it took such remarks "very seriously" and would do everything to prevent bin Laden from acquiring such weapons of mass destruction.
"I wish to declare that if America used chemical or nuclear weapons against us, then we may retort with chemical and nuclear weapons. We have the weapons as deterrent," Dawnquoted bin Laden as telling a well-known Pakistani journalist in Afghanistan on Wednesday night.
Asked where he got the weapons, bin Laden replied: "Go to the next question," the newspaper said.
Dawnsaid Mr Hamid Mir, editor of Pakistan's Ausafnewspaper, had interviewed bin Laden on behalf of the two newspapers after being taken blindfold by jeep from Kabul on November 7th.
It was not immediately possible to verify the report, but Mr Mir told reporters his account of the interview was correct.
Independent experts say it is unlikely bin Laden has developed a nuclear capability.
The paper, which printed a photograph showing Mr Mir with bin Laden, said it was the first interview the Saudi-born militant had granted to any journalist since the deadly September 11th attacks on the World Trade Centre and the Pentagon for which he is the prime suspect.
"We have said that we have suspected all along that this organisation has been pursuing the acquisition of chemical, biological and nuclear materials," said White House spokesman Mr Ken Lisaius.
Pakistan's government last month dismissed as absurd some international media reports that bin Laden had obtained nuclear material from the arsenal of the nuclear capable country.
Dawn said Mir was taken to a location where it was extremely cold and where he could hear the firing of anti-aircraft guns.
Bin Laden then appeared with about a dozen bodyguards and Ayman Zawahri, a top lieutenant in his al Qaeda network, the newspaper said.
In the interview, bin Laden said the September 11th attacks were justified but did not claim responsibility for them.
"The September 11 attacks were not targeted at women and children. The real targets were America's icons of military and economic power," bin Laden was quoted as saying.
"The American people should stop the massacre of Muslims by their government."
There was no way of telling when the photograph showing bin Laden with Mir was taken, but the editor is known to have never previously met bin Laden.
The picture showed bin Laden wearing a white turban and a camouflage jacket over a long white tunic. A Kalshnikov assault rifle was propped up beside bin Laden on the cushions he was sitting on.
The newspaper quoted bin Laden as saying he was fighting a defensive struggle to protect Muslims.
"This is a defensive jihad. We want to defend our people and our land. That is why I say that if we don't get security, the Americans, too, would not get security," he was quoted as saying.
"This is a simple formula that even an American child can understand. This is the formula of live and let live."
Dawnreported that bin Laden said he was engaged in a historic struggle on behalf of Muslims.
"Right now a great war of Islamic history is being fought in Afghanistan. All the big powers are united against Muslims," it quoted bin Laden as saying.