An Iranian opposition group said Thursday that Iran's fundamentalist government is racing to produce several types of lethal chemical and biological weapons, dedicating up to 11,000 workers at numerous factories and research facilities.

The National Council of Resistance of Iran (search) said Iran has already weaponized deadly agents anthrax, smallpox and typhoid and has the missiles to use them throughout the region.

"I can tell you this, that if they decide right now to use these biological microbial weapons, they can use it in a very, very deadly manner that could inflict heavy and widespread human damages," said AliReza Jafarzadeh, a representative of the People's Mujahedin (search), a member group of the council.

Another representative of the group said Iran has used outside scientists to speed up the work and specified labs, companies, military organizations and leaders they said were involved.

"Weapons experts from China, North Korea, India, Russia are cooperating with the ministry of defense," said Soona Samsami, who cited clandestine sources but did not provide evidence.

The United States has long suspected Iran was pursuing chemical and biological weapons. In February, CIA Director George Tenet (search) told Congress that Iran was in the process of seeking outside help to develop chemical and biological weapons and said the work was only in the preliminary stages.

Iran was not listed in a recent U.S. listing of nations with smallpox samples and as a member of the 1972 Biological Weapons Convention, Iran denies having any.

But the opposition group said Iran has the toxic agents and the missiles to deliver them.

"Our sources have confirmed that if decided today, the Iranian regime is capable of delivering deadly blows and inflicting massive casualties, human casualties," Jafarzadeh said.

The United States takes the allegations very seriously, but the opposition group has a dark history of its own. The People's Mujahedin is a Marxist-Islamist armed opposition group that has operated in Iraq for years, and until Operation Iraqi Freedom, sympathized with Saddam Hussein's Baathist government.

The group is also a six-year member of the State Department's list of terrorist groups. It has been blamed with carrying out assassinations and bombings in Iran in an effort to overthrow the fundamentalist government.

Coalition forces surrounded and fired upon the People's Mujahedin during Operation Iraqi Freedom. It later took control of its heavy weaponry.

"Some of our actions involve targeting them with lethal fires. At this point, a cease-fire is in effect," said Central Command (search) spokesman Brigadier General Vincent Brooks.

The National Council of Resistance has challenged its designation as a terrorist group, saying it has only been listed in a U.S attempt to appease elements within the Iranian government.

But a federal appeals court said last week that a review of public records was enough to convict the group "even without repairing to the classified information submitted to the court."

Despite their standing, the group has been ahead of the curve on other developments in Iran. For example, it exposed Iran's Natanz Uranium Enrichment Facility, part of a nuclear weapons program now under investigation by the International Atomic Energy Agency (search).

Fox News' Major Garrett contributed to this report.