"We are aware of this, but have no comment at this point in time," said Melissa Fleming, a spokeswoman for the Vienna-based International Atomic Energy Agency.

"As with all new information coming our way, our analysts take a serious look and decide whether it would warrant a follow-up," Fleming added.

According to the exiled National Council of Resistance of Iran, Tehran is actively pursuing a nuclear weapons programme, despite a recent US intelligence report which had said that Iran had abandoned such a programme in 2003.

A senior member of the group, Mohammad Mohadessin, presented reporters in Brussels with information he said had been collected on two sites in Iran on top secret studies on nuclear warheads.

Mohadessin said the site at Khojir, in a Tehran suburb, was an Iranian defence ministry missile-research site which is developing a nuclear warhead for medium-range missiles.

He described the other facility, in another Tehran suburb, as the "command and control centre" for production of a nuclear bomb.

This is not the first time the group has claimed to have information about Iran's alleged nuclear programme.

Its latest declaration comes just days before the latest assessment on Iran's disputed atomic drive by IAEA chief Mohammed ElBaradei.

ElBaradei's report, which diplomats in Vienna said could be released as early as Friday, will be crucial for the UN Security Council in deciding whether to slap further sanctions on Iran in the long-running nuclear stand-off.

The claims run counter to a US intelligence report released in December which said Iran halted its nuclear weapons programme in 2003.

That US report led to calls from Tehran, and some other quarters, for UN sanctions against the Iranian regime to be dropped.

"The Iranian regime is undoubtedly developing a nuclear bomb," Mohadessin said, adding that the information had been handed over to the IAEA on Tuesday.

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.