A team of senior UN nuclear officials could visit Iran in January, the Islamic state's ambassador to the International Atomic Energy Agency (IAEA) has told Reuters.

Ali Asghar Soltanieh said on Tuesday that Iran had renewed its invitation for an IAEA team to travel to Tehran. He suggested that Iranian officials would be ready to discuss international concerns about the country's nuclear programme.

He later gave further details in an interview with Reuters television on Wednesday evening, saying preliminary arrangements for the visit would be made in the first week of January.

"Any time after that, after the composition of the team is finalized, they are welcome to come. Therefore, I assume that, perhaps in January, this visit will be made," Soltanieh said.

Iran's latest overture to the Vienna-based UN agency, which has long urged Tehran to address disputes about its nuclear agenda, coincides with a sharpening of international sanctions imposed on Iran over its nuclear work.

Western diplomats tend to see such invitations as attempts by Iran, a major oil producer, to buy time and ease international pressure without heeding UN demands to curb activity that could go towards making atomic bombs and to be transparent about its programme to ease misgivings about it.

One Western envoy this week dismissed Iran's new offer of talks as part of a "charm offensive" without any commitment from Tehran "to talk substance."

Iran says it is enriching uranium solely for peaceful purposes, but its foes suspect this has military aims.

Western fears that Iran is seeking to develop atomic bomb capability were reinforced by an 8 November IAEA report that said Tehran appeared to have worked on designing a nuclear weapon.

Suspicions stoked by secrecy

Suspicions have been stoked by Iranian secrecy and lack of full cooperation with inspectors from the IAEA, whose job is to verify that countries' nuclear activities are peaceful.

Iran says its nuclear work is a peaceful bid to generate electricity so that it can export more of its oil and gas.

Iran initially invited Herman Nackaerts, IAEA deputy director general and head of nuclear safeguards inspections worldwide, in October. But Iran's angry reaction to the agency report the following month threw those plans into doubt.

Previous visits to Iran by senior IAEA officials have failed to make significant progress towards resolving the long-running row over Iran's nuclear programme, a dispute which has the potential to ignite a wider conflict in the Middle East.

IAEA inspectors monitor Iran's declared nuclear sites but their movements are otherwise restricted.

IAEA Director-General Yukiya Amano has made clear that any new visit by his senior officials to Tehran must address the agency's growing concerns about potential military dimensions to the nuclear programme.

An IAEA spokeswoman said on Wednesday the agency was "working on a possible visit" to Iran, without elaborating.