US President George W. Bush charged Monday that Iran has openly declared that it seeks nuclear weapons -- an inaccurate accusation at a time of sharp tensions between Washington and Tehran.

"It's up to Iran to prove to the world that they're a stabilizing force as opposed to a destabilizing force. After all, this is a government that has proclaimed its desire to build a nuclear weapon," he said during a joint press conference with Afghan President Hamid Karzai.

But Iran has repeatedly said that its nuclear program, which is widely believed in the West to be cover for an effort to develop atomic weapons, is for civilian purposes.

Asked to provide examples of Tehran openly declaring that it seeks atomic weapons, White House officials contacted by AFP said that Bush was referring to Iran's defiance of international calls to freeze sensitive nuclear work.

They explained that he was referring to Tehran's uranium enrichment -- a process that can yield nuclear bomb material -- and resulting worries by the UN nuclear watchdog, the International Atomic Energy Agency (IAEA).

"After keeping their nuclear program secret for a decade, the Iranian government has refused the offers of the international community to provide nuclear energy and continues to flout the inspectors of the IAEA," said national security spokesman Gordon Johndroe.

"Unfortunately, their intentions seem clear," Johndroe said.