The move reveals a "major escalation" in clandestine operations aimed at destabilizing the Islamic republic's religious leadership amid concerns over Tehran's nuclear ambitions, said the report in the New Yorker magazine citing former military, intelligence, and congressional sources.

Among the methods being used are increased US support for minority and dissident groups and intelligence gathering about Iran's nuclear facilities, said the article, written and reported by Seymour Hersh.

Although such covert activities in Iran are not new on the part of the United States, the magazine said the "scale and the scope of the operations in Iran, which involve the Central Intelligence Agency and the Joint Special Operations Command (JSOC), have now been significantly expanded."

The Congress approved Bush's request for funding late last year, according to sources with knowledge of the top secret Presidential Finding, which by law must be issued when covert intelligence operations get underway.

The Presidential Finding is conveyed to a select group of Congressional leaders and their intelligence committees, otherwise known as the Gang of Eight, the report said.

"The Finding was focused on undermining Iran's nuclear ambitions and trying to undermine the government through regime change," and involved "working with opposition groups and passing money," the report said, quoting an unnamed "person familiar with its contents."

The report said some lawmakers were skeptical of the administration's aims, and there was "a significant amount of high-level discussion" about the Finding before the funding was eventually approved.

The Bush administration's request for funding came around the same time as the December 2007 release of the National Intelligence Estimate, which said the Iran halted nuclear weapons work in 2003.

The NIE was downplayed by Bush and other officials who called for urgent action to counter the Iranian nuclear threat.

Washington suspects Iran is secretly working to build an atomic weapons arsenal. Iran insists its nuclear activities are for civilian energy purposes.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.