Iran agreed yesterday to let inspectors from the United Nation's nuclear watchdog revisit its heavy-water reactor site early next week in a push by the UN for more transparency in Iran's disputed nuclear program.

Diplomats said the accord, which came in a second round of negotiations between Iran and the International Atomic Energy Agency (IAEA) to clarify the scope of Iran's atomic activities, was a bid by Teheran to head off more painful UN sanctions.

Olli Heinonen, the IAEA's deputy director in charge of nuclear safeguards, said Iran agreed to let inspectors return to the Arak heavy-water complex, which is under construction, next Monday or Tuesday - four months after Iran cut off IAEA access there in protest at existing sanctions.

Inspectors want to check that Iran is adhering to design data for the reactor given earlier to the IAEA. Diplomats say the risk of Iran using the reactor to process weapons-grade plutonium would rise in the absence of UN monitoring.

Iran says it wants to refine uranium only for electricity so it can export more of its oil wealth. But it has been slapped with two sets of sanctions for defying UN resolutions demanding it suspend all efforts to produce nuclear fuel.

European diplomats said last week Western powers had quietly shelved efforts to toughen penalties against Iran until September to see whether the talks would bring an end to Iranian stonewalling of UN inquiries since 2003 and defuse a volatile standoff between Teheran and Western powers.

The inspection trip to Arak next week will be a one-off gesture, not a resumption of regular IAEA visits for design verification which Iran has yet to restore, diplomats said.

After meeting Iran's deputy nuclear negotiator Javad Vaeedi in Vienna, Heinonen said the next step would be to clear up other IAEA questions, such as past Iranian experiments with plutonium and the extent of its uranium enrichment program.

Vaeedi said he would resume talks with Heinonen in Teheran on August 20: "We had a good discussion and constructive progress in this meeting (today). Now we are going to move forward in the best mood and with the best effort," he said.

Neither man took questions from reporters.

Analysts said Teheran could be forthcoming on some points of IAEA inquiries but hesitate on others to retain bargaining chips in a drawn-out strategic poker match with Western powers.

(China Daily via agencies July 25, 2007)