Officials from six world powers are expected to meet on Monday to consider ways to increase pressure on Iran, as Tehran vows to carry on with its sensitive nuclear work.
Representatives from the United States, Britain, France, Russia and China -- which comprise the UN Security Council -- will meet in London. German officials also will attend.
Iran ignored a Security Council deadline to suspend uranium enrichment by February 21 or face the risk of UN sanctions on top of those imposed in December.
On Sunday, Iranian state media quoted President Mahmoud Ahmadinejad as saying Iran will not halt its nuclear program. Mr. Ahmadinejad said Iran's development of technology for producing nuclear fuel is like a train -- in his words -- with "no brakes and no reverse gear."
US Secretary of State Condoleezza Rice later said on Fox News that Iran needs to stop enriching uranium. She repeated offers to meet with Iranian officials if Tehran suspends its controversial nuclear activities.
The United States and other Western powers suspect Tehran is trying to develop nuclear weapons -- a charge Tehran denies.
Separately, Iranian media quoted a deputy foreign minister Manouchehr Mohammadi as saying Tehran is prepared for any situation in its nuclear dispute with the West, even war.