Iranian opposition officials say that Iran is not only supporting and harboring terrorists, including Al Qaeda members, but also is working hard to develop chemical and nuclear weapons.

Members of an Iranian opposition group in Washington, D.C., Wednesday said they have specific evidence of two locations inside Iran -- in the cities of Natanz and Arak, located south of the capital of Tehran -- where there are covert operations to make a nuclear weapon.

"These two secret sites are away from the monitoring of the international atomic energy agency and the purpose of these sites is both for the production of nuclear fuel and also the research and expertise to be able to make the bomb," said Ali Reza Jafarzadeh, a member of the National Council of Resistance of Iran.

U.S. officials said that the information is being taken seriously and is being analyzed, and senior defense officials confirm that intelligence shows that Iran is "desperately seeking" nuclear fuel capability -- fissile material for a nuclear bomb.

Officials are treating the information cautiously because it comes from the NCRI, which is listed as a foreign terrorist organization by the State Department.

"We consider the so-called NCRI -- National Council of Resistance of Iran -- we consider them to be a foreign terrorist organization," said deputy State Department spokesman Philip Reeker.

One official told Fox News that the broad fight against terrorists and states that sponsor terrorists makes for strange bedfellows.

The Bush administration has high hopes that a growing opposition in Iran will overthrow the current regime and create a democratic government before long, unlike in Iraq, where U.S. officials see no signs of an effective internal effort to get rid of Iraqi President Saddam Hussein.

Tuesday, the president of Iran, Mohammad Khatami, met with Afghan President Hamid Karzai. In recent days, Iranian leaders have said the country is cracking down on Al Qaeda, arresting terrorists and transporting them to other countries, including 16 who have been sent to Saudi Arabia.

Defense Secretary Donald Rumsfeld brushed off the contributions, saying there is no question that Iran is permitting Al Qaeda terrorists to exist in its borders. And the Pentagon still considers Iran to be one of the most dangerous countries supporting terrorists and striving for weapons of mass destruction.

Fox News' Bret Baier contributed to this report.