"We're optimistic that the board of governors is going to send a very strong and unified message to Iran that it needs to come clean about its nuclear programme," Xinhua quoted US State Department spokesman Mark Toner as saying.

"As we've said many times, the international community, the P5- plus-one is increasingly concerned about Iran's inability to address the international community's concerns about its nuclear programme," he said.

Earlier in the day, IAEA Director General Yukiya Amano said the information contained in the agency's latest report on Iran's nuclear programme is credible.

The report alleged that Iran had carried out "organised and systematical" activities "specific to nuclear weapons" at least until the end of 2003.