An Iranian opposition group said Friday that Tehran's leaders have consolidated several scattered nuclear research efforts in a single new defense agency geared to streamline weapons development.

The Mujahedin-e Khalk, or MEK, told The Associated Press that Iran's defense ministry established the new agency in March to merge various nuclear-related programs.

The State Department had no immediate comment on the report. Some of MEK's past claims about Iran's nuclear program have been confirmed, while others have not. But a former international nuclear inspector said Friday he has heard a similar report.

An MEK spokesman said the new agency, the Organization for New Defense Research is led by Moshen Fakhrizadeh, a physicist long suspected of running Iran's secret nuclear projects.

The U.N. Security Council placed Fakhrizadeh under an asset freeze and travel ban after Iran refused to make him available to International Atomic Energy Agency investigators.

Iran has repeatedly said it is interested only in the peaceful uses of nuclear technology. The United States and many other countries believe Iran is laying the groundwork for building a bomb, though it is not clear if it has committed itself to doing so.

MEK spokesman Alireza Jafarzadeh said Iran's clear goal is to join the club of nuclear weapons states. "This is a very advanced, sophisticated nuclear weapons program with all the necessary elements to build a nuclear weapon," Jafarzadeh said.

Jafarzadeh said Iran has merged its secret nuclear programs because it believes it can continue to deny international inspectors access to sensitive sites and scientists like Fakhrizadeh.

"They have learned how to dodge the international community, how to obtain what they need using front companies," Jafarzadeh said.

Olli Heinonen, the former International Atomic Energy Agency deputy director in charge of Iran, said that he has received similar information, although he was told that the new Iranian agency reports to the Islamic Revolutionary Guard Corps rather than the Ministry of Defense.

Heinonen, now a senior fellow at Harvard's Belfer Center, said he was told the reorganization was part of an effort by Ayatollah Ali Khamenei, Iran's Supreme Leader, to remove President Mahmoud Ahmadinejad from the nuclear research effort's chain of command.

According to an intelligence assessment shared with The Associated Press, Ahmadinejad wants to shed the nation's secrecy and forge ahead openly with developing nuclear weapons. He is opposed by the clerical leadership, which is worried about international reaction to such a move. The assessment was produced by a nation with traditionally reliable intelligence from the region.

Ahmadinejad is pushing "to shake free of the restraints Iran has imposed upon itself, and openly push forward to create a nuclear bomb," says the assessment. But Khamenei, whose word is final on nuclear and other issues, "wants to progress using secret channels, due to concern about a severe response from the West," says the report.

The MEK, which is dedicated to the overthrow of the regime in Tehran, is currently lobbying the Obama administration to be removed from the State Department's list of terrorist organizations.

The group committed a series of bombings and assassinations in Iran in the 1970s and early 1980s, and fought on the side of Saddam Hussein during the Iran-Iraq war. But MEK says it renounced violence in 2001, and that its extensive network of sympathizers inside Iran produces valuable intelligence.

The group has built bipartisan support among many members of Congress and former senior U.S. government officials, although it is regarded with skepticism by many diplomats and academic specialists. Some analysts suspect MEK has ties to Western intelligence services, but the group has denied this.

Jafarzadeh said the headquarters of Iran's new nuclear organization, known by its Farsi acronym SPND, is located adjacent to the Malik Ashtar University of Technology in northeast Tehran.

The SPND's six sections include a directorate as well as research labs for physics, metallurgy, chemistry, explosives and nuclear safety, he said.

The MEK spokesman said Iran's nuclear organization evades sanctions and buys advanced technology — including devices that measure a person's exposure to radiation and the triggers for nuclear weapons — through a variety of front companies.

Associated Press Writer George Jahn in Vienna contributed to this report.