A fresh round of talks between the United Nations nuclear watchdog and Iran has been taking place at the International Atomic Energy Agency's (IAEA) headquarters in Vienna.
Officials of the IAEA were expected to press Iran to agree to a new deal under which UN inspectors would be permitted to visit sites where Tehran is suspected of working on an atomic bomb.
Iran says it nuclear program, including uranium enrichment work, is for peaceful purposes only and has no weapons component.
Chinese President Hu Jintao, who met with Iranian President Mahmud Ahmadinejad in Beijing this week, was quoted as urging that Iran be "flexible and pragmatic" in talks about its nuclear program.
China and Russia have lately been opposing Western efforts for new sanctions against the Islamic republic over the nuclear issue. But Moscow and Beijing have stressed that Iran's program must be peaceful.
The nuclear issue was also discussed this week in talks between Ahmadinejad and Russian President Vladimir Putin.
The Iranian delegation to the Vienna talks was led by Iran's ambassador to the IAEA, Ali Asghar Soltanieh.
Soltanieh earlier this week accused the IAEA of acting like an "intelligence agency" because of what Soltanieh said was the agency's reliance on Western intelligence information about Iranian sites.
Of particular interest to IAEA inspectors is the Parchin military site southeast of Tehran, where parts for nuclear warheads are alleged to have been tested.
The nuclear watchdog has been seeking access to Parchin for months but so far has been denied by Tehran. Iran says the site is not linked to its nuclear program and so it is not obliged to allow inspections.
But the IAEA has cited recent satellite images it says suggest "extensive activities" at Parchin, including the razing of two buildings, in what experts say could be signs of a clean-up following explosives tests.
The IAEA wants Iran to agree to a so-called "Structured Approach" document, which asks Iran to answer only the IAEA's questions about the possible military dimensions of its nuclear program.
The document does not cover other major outstanding issues in the Iran nuclear crisis, such as Iran's failure so far to ratify an additional protocol authorizing IAEA inspectors to make unannounced checks of any and all nuclear facilities when and where the inspectors may want.
Nor does it cover the UN Security Council's demand that Iran suspend uranium enrichment work that could be directed toward development of a nuclear weapon.
Iran has repeatedly vowed to continue uranium enrichment to 20 percent -- a level opposed by Western nations because it moves Tehran closer to being able to produce highly enriched material that could be used in a weapon.
Separate from the IAEA meetings, Iran and six world powers -- Britain, China, France, Germany, Russia, and the United States -- are preparing to hold another round of talks on the nuclear issue in Moscow on June 18-19. The same sides held inconclusive talks in Baghdad in May.
Westen powers in recent months have tightened sanctions on Iran by targeting the Islamic republic's banking sector and oil exports, Tehran's chief source of foreign revenue. The European Union is planning to halt imports of Iranian oil as of July.
Iran is also already under four rounds of UN Security Council sanctions aimed at pressing Tehran to suspend uranium enrichment.
With reporting by AFP, dpa, Reuters, and IRNA