An Iranian opposition leader said Thursday that the country is making sweeping changes to its security apparatus in an effort to consolidate the power of the elite Revolutionary Guard.

Maryam Rajavi, head of the National Council of Resistance of Iran — a Paris-based umbrella opposition group — said the alleged changes and accompanying purges stem from worries about the loyalty of the security forces as the nation experiences its most significant unrest since the 1979 Islamic Revolution.

Iran had announced a reorganization of its security forces following President Mahmoud Ahmadinejad's disputed re-election in June. But the changes Rajavi contended are taking place have so far been unknown.

The Paris-based National Council of Resistance has frequently made accusations about Iran's covert activities, based on what it says is information from sources inside the country. Some of its claims have been borne out; others have not been substantiated.

A spokesman for the Iranian embassy in Brussels declined comment Thursday on Rajavi's latest claims.

The Revolutionary Guard, directly controlled by Supreme Leader Ayatollah Ali Khamenei, has in recent years expanded its influence into key economic and technological sectors, including the nation's nuclear program. It operates independently of the armed forces and maintains a nationwide network of militia groups, known as Basij.

Rajavi said authorities in Iran have concealed the extent of the changes to the security structure.

"The new organization, the Intelligence Organization of the Islamic Revolutionary Guard Corps, will from this point onward act as the regime's main security force," Rajavi told journalists Thursday in Brussels.

She said that Hossein Taeb, previously commander of the Basij militia, has been named to head the new agency.

"Its command structure is linked directly to Khamenei (and) its formation marks an unprecedented transformation for the regime's intelligence and suppressive apparatus," Rajavi said.

She said the guard's intelligence agency will incorporate seven existing security organizations. These include sections of the Internal Security Directorate and Ministry of Intelligence and Security, the Security Directorate of the Basij force, anti-riot forces and the main security headquarters for Tehran, Rajavi said.

"The objective is to centralize the intelligence and security organs in a way that makes the new organization dominant and the Ministry of Intelligence and Security subservient," she said. "The new organization will be directly controlled by Khamenei (and) will not be dependent on the president or the Majlis (parliament)."

In 2002, the National Council of Resistance of Iran disclosed the existence of two previously secret nuclear facilities — a pilot uranium enrichment plant at Natanz and a research reactor being built in the city of Arak, which turned out to house Iran's uranium enrichment program and a hard-water reactor project.

The council is regarded as a terrorist organization by the United States.