The head of the UN nuclear agency voiced growing frustration at Iran's failure to address allegations of possible military aspects to its nuclear programme, saying new information added to his concerns.
"We are not saying that Iran has a nuclear weapons programme. We have concerns and we want to clarify the matter," Yukiya Amano, director general of the International Atomic Energy Agency (IAEA), told a news conference.
He said the IAEA had received since late last year some "information raising further concern", without giving details.
Iran denies Western allegations it is seeking to develop a nuclear weapons capability, saying its atomic activities are aimed at generating electricity.