A smoldering covert war pitting the United States against Iran took a new turn this week as Iranian officials announced the arrests of a dozen “CIA spies” they said were targeting the country’s nuclear program.

Iranian officials, including the country’s intelligence minister, did not release the identities or nationalities of the alleged spies, but intelligence analysts say they are probably Iranians working as informants for Western intelligence services.

“The main mission of this act of espionage was related to Iran’s progress in the fields of nuclear technology and also military and security activities,” said Parviz Sorouri, a member of Iran’s powerful parliamentary committee on national security and foreign policy, according to the official IRNA news agency. “The US and Zionist regime’s espionage apparatuses were trying to damage Iran both from inside and outside with a heavy blow, using regional intelligence services.”

The potential “CIA arrests” followed reports earlier in the week of other arrests in Iran. There were also reports that Hezbollah, the Iran-affiliated Shiite militia in Lebanon, has arrested alleged CIA informants.

The latest Iranian allegations could not be verified, and the Central Intelligence Agency declined to comment, as it does as a rule on “operational activities.” But the charges were the latest installment in a growing list of covert operations – or accusations claiming such operations. That list includes the killing of Iranian nuclear scientists, explosions at Iranian factories and military installations, cyberattacks targeting Iran’s nuclear facilities, and – on the other side – the alleged Iranian plot to assassinate the Saudi ambassador to Washington.

Iran has for years accused the US of working in conjunction with Israeli intelligence to thwart Iran’s nuclear program through covert operations. Many analysts assume that the Stuxnet computer worm that affected machines in Iran’s nuclear installations between June 2009 and the end of 2010 was developed in Israel with US assistance.

US officials have declined to acknowledge American involvement in the covert operations including Stuxnet. But Secretary of State Hillary Rodham Clinton did claim early this year that the virus and other “technological difficulties” had set back Iran’s nuclear progress.

Richard Clarke, a former White House terrorism adviser and author of the book, “Cyber War: The Next Threat to National Security and What to Do About It,” cites Stuxnet as a poster child for cyberwarfare.

The covert war on Iran’s nuclear program has advanced as diplomatic efforts have faltered, which have left Western powers with the option of economic sanctions for curbing Iran’s nuclear ambitions.

But some Iran analysts credit a tandem reliance on covert operations and economic sanctions as slowing Iran’s nuclear progress – and thus as quieting the chorus of hawkish voices calling for airstrikes on Iran’s nuclear facilities.

On the other hand, the US presidential campaign has provided a venue for one-upmanship among candidates in terms of dealing with Iran. Some Republican candidates have inched closer to support for airstrikes on Iranian nuclear facilities.

The campaign has also provided a stage for discussion of the merits of covert operations against Iran, as well as for some acknowledgement that a covert war already exists.

Former Speaker Newt Gingrich has taken to recommending covert US operations in Iran – drawing mocking retorts from Democrats who say that Mr. Gingrich’s idea is behind the curve.

Earlier this week retired Gen. Wesley Clark, a former Democratic presidential aspirant, accused some Republican candidates of “rattling the sabers for war with Iran.” He then singled out Gingrich for talking up covert action as if it were an untried option.

“One candidate” was “placing heavy emphasis on covert action as though he had just invented the idea and nothing is happening now,” Mr. Clark said, referring to Gingrich. He called the notion “a little bit cute, since the definition of covert action is that it cannot be acknowledged."