An exiled Iranian opposition group claimed Wednesday that Tehran was speeding up a program to develop nuclear weapons. "The Iran regime entered a new phase in its nuclear project," said Mohammad Mohaddessin of the Paris-based National Council of Resistance of Iran.

The NCRI is the political wing of the People's Mujahedeen of Iran, which advocates the overthrow of government in Tehran. The Mujahedeen has been designated a terrorist group by the United States and the European Union as well as Iran.

Mohaddessin claimed that Tehran has established a command and research center near a Tehran university. And, he said, Iran is developing a nuclear warhead for use on medium-range missiles at a site on the southeast edge of Tehran. Mohaddessin also claimed that the regime obtained aid from North Korea.

It was not possible to independently verify the NCRI claims. Mohaddessin said his group got the information from "hundreds" of reports and sources from within the Iranian regime, whom he did not name. He said some of the sources are within the nuclear project itself.

An official of the International Atomic Energy Agency, who spoke anonymously because he was not authorized to talk to the media, said the agency was aware of the allegations. Mohaddessin said he had provided information to the IAEA on Tuesday.

Iran has steadfastly denied it is working to obtain a nuclear bomb, arguing that its nuclear program is civilian.

A recent U.S. National Intelligence Estimate said Iran halted a nuclear weapons development program in 2003 because of international pressure. But the White House said Iran continues to hide information, remains in violation of two U.N. Security Council resolutions, tests ballistic missiles and is enriching uranium, which can be used to build an atomic bomb.

Four years ago, the group disclosed information about two hidden nuclear sites in Iran. But much of the information it has presented since to support claims of a secret weapons program has not been publicly verified.