Vienna ? The U.N. nuclear agency on Thursday said it was worried Iran may currently be working on making a nuclear warhead, suggesting for the first time that Tehran had either resumed such work or never stopped at the time U.S. intelligence thought it did.

The report by the International Atomic Energy Agency appeared to put the U.N. nuclear monitor on the side of Germany, France, Britain and Israel. These nations and other U.S. allies have disputed the conclusions of a U.S. intelligence assessment published three years ago that said Tehran appeared to have suspended such work in 2003.