Olli Heinonen, the International Atomic Energy Agency (IAEA) deputy director general for safeguards, will seek to shape a plan to resolve "outstanding issues" over Iran's nuclear programme during his two-day visit.

The visit comes just days after the head of the IAEA said Tehran had slowed expansion of its uranium enrichment, the process at the centre of Western fears Iran may be seeking to build the bomb.

The five-member delegation will first meet Iran's national security chief and top nuclear negotiator Ali Larijani, who met EU foreign policy chief Javier Solana last month over the crisis.

The officials will then have in-depth discussions on Wednesday and Thursday with Larijani's number two, Iran's ambassador to the IAEA, Ali-Asghar Soltanieh, told state radio.

The results of the talks would be made public on Friday, Soltanieh added.

However, Iranian officials said Heinonen will not be inspecting any nuclear sites, such as at Natanz in central Iran where uranium enrichment is currently carried out.

On Monday, a US think tank reported that commercial satellite imagery indicated Iran is tunnelling into a mountain near the Natanz complex, possibly to protect the facility against air attack.

Ahead of Heinonen's visit, IAEA chief Mohamed ElBaradei said that "drawing up a plan of action" should take 60 days. Implementation would then begin on resolving questions about Iranian nuclear activities that could have military applications.

"We have seen a fairly slow development in commissioning new cascades," ElBaradei told reporters on Monday, referring to the installation of centrifuges which enrich uranium into fuel for civilian reactors or, in its highly refined state, nuclear bomb material.

ElBaradei has also called on Iran to freeze uranium enrichment at current levels, in return for the United Nations holding off on threatened new sanctions.

But Britain and Tehran's arch-foe, the United States, have again warned the Islamic republic about its nuclear programme which the West fears could be a cover to build a nuclear bomb.

Britain said it will press for a third UN resolution to tighten sanctions on Iran if it continues to defy calls to suspend enrichment, while US Secretary of State Condoleezza Rice has refused to rule out military action.

Iran's refusal to address IAEA questions and its resumption of enrichment activities, which it had suspended for more than two years, prompted the world body to refer Iran to the UN Security Council in February 2006.

The council has adopted three resolutions demanding that Iran address IAEA concerns and suspend enrichment, and has imposed two sets of sanctions against Tehran for its continued refusal to suspend the controversial process.

Iran has so far rejected any halt in its uranium enrichment programme, which it says is aimed solely at making fuel for its growing energy.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.