IAEA visits Iran's Arak heavy water atom site- IRNA

TEHRAN, July 30 (Reuters) Inspectors from the United Nations nuclear watchdog conducted a five-hour visit to Iran's heavy-water reactor site at Arak today, the official IRNA news agency said, the first such visit there since April.

Iran agreed on July 24 to let inspectors from the International Atomic Energy Agency (IAEA) visit the complex early this week, as part of a U.N. push for more transparency in Iran's disputed nuclear programme.

Four months ago Iran cut off IAEA access to Arak, southwest of the capital Tehran, to protest at UN sanctions against Tehran over its refusal to halt atomic work Western powers suspect is aimed at making nuclear bombs. Iran denies the charge.

IRNA, which quoted what it described as an informed source, did not provide further details about the visit. IAEA officials in Vienna had no immediate comment.

''Inspectors from the International Atomic Energy Agency visited Arak's 40 megawatt research reactor today,'' IRNA quoted its source as saying.

Western diplomats say Iran is showing signs of cooperation with the Vienna-based agency to head off broader, more painful UN sanctions.

The Arak complex is under construction and due for completion in 2009.

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 yield bomb-grade plutonium would rise in the absence of UN monitoring.

Iran says its nuclear programme, centred on a new uranium enrichment plant in Natanz, is meant to generate electricity so it can export more of its oil wealth -- not bombs as Western powers suspect after years of Iranian secrecy and evasions.

But it has been slapped with two sets of sanctions for defying repeated UN resolutions demanding it suspend all nuclear fuel activity, including the Arak project.

European diplomats said earlier this month Western powers had quietly shelved steps to toughen penalties against Iran until September to see whether the IAEA negotiations would bring an end to Iranian obstruction of UN inquiries since 2003 and end a standoff between Tehran and Western powers.

REUTERS JT KP2107