Iranian President Mohammad Khatami (right) at the Natanz nuclear plant on Wednesday. (AFP)

Natanz (Iran), March 30 (Reuters): Iran?s President Mohammad Khatami took a group of journalists deep underground today into the heart of a key nuclear plant which Washington wants dismantled and whose existence was kept secret until 2002.

About 30 local and foreign journalists visited Natanz uranium enrichment facility, 250 km south of Tehran, the centrepiece of a disputed atomic fuel drive which Tehran suspended under international pressure in late 2003.

The unprecedented visit was an unusual gesture of openness by the Islamic state. Reporters, allowed to photograph and film the complex, were later shown parts of another atomic facility in Isfahan.

Iran says its nuclear programme is nothing for the world to fear and will only be used to generate much-needed electricity. But Washington and the European Union fear Iran could use its nuclear plants to produce bombs.

The journalists, invited to accompany Khatami on a tour of the 450-hectare site, were taken inside a building where, two levels below ground, they were shown a vast empty hall designed to house 50,000 enrichment centrifuges.

Centrifuges purify uranium fluoride gas into reactor or bomb fuel by spinning at high speeds. Low-grade enriched uranium is used in atomic power plants but highly enriched uranium can be used in the core of a bomb. ?If we were looking to make atomic weapons...we could have completed these (facilities)...in hiding,? Khatami said.

The journalists were not shown any centrifuges and were not taken to a pilot enrichment facility in Natanz which contains dozens of machines, currently idled while Iran discusses the future of its nuclear programme with the EU.