The United Nations nuclear watchdog confirmed on Saturday it will resume talks with Iran in mid-May, more than two months after the last meeting over concerns about the Islamic state's atomic activities ended in failure.

Gill Tudor, spokeswoman for the International Atomic Energy Agency, said the meeting would take place on May 14-15 at the Iranian diplomatic mission in Vienna.

"The purpose is to continue the negotiations started early this year," Tudor said in an email.

She was commenting on a report on Friday by the official Iranian news agency IRNA, which quoted Iran's envoy to the IAEA Ali Asghar Soltanieh as saying talks would resume.

Washington and its allies believe Tehran is working on developing nuclear bombs.

Tehran insists its activities have only civilian aims and has refused to stop enriching uranium, despite a slew of sanctions.

The IAEA last year issued a report detailing alleged Iranian research and development activities that were relevant to nuclear weapons, lending independent weight to Western suspicions.

The IAEA wants Iran to address the questions raised in the report. Iran has dismissed Western allegations as fabricated.

Soltanieh told IRNA Tehran's decision to resume talks "shows the peaceful nature of all of its nuclear activities, while showing that claims against Iran are baseless."

Western diplomats said last week Tehran still appeared to be stonewalling over the body's most pressing demand to let its inspectors visit a key military site.

Iran has also restarted negotiations with six world powers over its nuclear program and the sides have agreed to meet again in Baghdad on May 23.

Iranian Foreign Minister Ali Akbar Salehi said on Monday Iran was optimistic that the talks with United States, Russia, China, Germany, France and Britain would make progress.