The five permanent members of the UN Security Council have stepped up the pressure on Iran to allay international concerns about its nuclear program.
The five -- the United States, France, Russia, China, and Britain -- on May 3 issued a statement urging Tehran to take concrete steps toward a negotiated solution.
They pressed Tehran to urgently allow the UN's nuclear watchdog, the International Atomic Energy Agency access to "relevant sites and information."
Iran and the five powers plus Germany resumed talks in mid-April in Istanbul after more than a year in what is seen as an opportunity to ease tensions.
They are to meet again on May 23 in Baghdad.
Tehran said on May 2 it would seek an end to sanctions over its nuclear activities at the Baghdad talks.
Based on reporting by Reuters and dpa