Work in progress at Iran's nuclear facilities

New Delhi: Satellite images show work going on at Iran's nuclear facilities. The pictures indicate Iran is building a new tunnel through a mountain near its reactor.

Analysts believe the construction could be a possible attempt to protect parts of its uranium enrichment program from aerial attacks.

The tunnel entrances are not visible in the satellite images. However, two roads under construction can be seen, with one appearing to lead into a tunnel.

In a report on Natanz first carried by The Washington Post, the website of the Institute for Science and International Technology showed commercial satellite photos taken in June that it said indicated construction of a mountainside tunnel near Natanz.

The tunnel could serve as extra protection for equipment and enriched uranium because Iran might fear ''that its underground halls at Natanz are vulnerable to destruction by military attack,'' said the institute.

A nuclear expert familiar with Iran's activities who asked for anonymity because his information was confidential told the AP that Iranian officials had told him Natanz was designed ''to withstand missile attack but not aerial attack.''

The IAEA declined comment. But a diplomat familiar with Iran's nuclear file said the agency was aware of the tunneling and had received unspecified ''clarification'' from Iran.

Iran's leaders say their country will never give up plans to assemble an industrial-scale nuclear program. Government officials have previously said that would include more than 50,000 centrifuges - enough to make the fissile core of dozens of weapons a year, should Iran go that route.

The IAEA began investigating Iran's nuclear activities only four years ago, after a dissident group revealed nearly two decades of a clandestine atomic program.

On North Korea, and the return of an agency team to the secretive communist country, ElBaradei cautioned that the IAEA mission - which is tasked with shutting down the country's plutonium-producing Yongbyon facility - was only beginning.

''It's going to be a long and complex process, but I welcome the return of the DPRK to the verification process,'' he said.

ElBaradei said timing for the visit depended on when the North Koreans issued an invitation, but he said he expected it to be ''in the next week or two.''

(With agency inputs)