Iran revealed for the first time Saturday that some personnel at the country's nuclear facilities were lured by promises of money to pass secrets to the West, but that increased security and worker privileges have put a stop to the spying.

The stunning acknowledgment by Iranian Vice President Ali Akbar Salehi provides the clearest government confirmation that Iran has been fighting espionage at its nuclear facilities.

Open gallery view Chief of Iran's Atomic Energy Organization Ali-Akbar Salehi. Credit: Reuters

In recent weeks, Iran has announced the arrest of several nuclear spies and battled a computer worm that it says is part of a covert Western plot to derail its nuclear program. And in July, a nuclear scientist who Iran says was kidnapped by U.S. agents returned home in mysterious circumstances, with the U.S. saying he was a willing defector who was offered $5 million by the CIA but then changed his mind.

The United States and its allies have vigorously sought to slow Iran's nuclear advances through United Nations and other sanctions out of suspicion that Tehran intends to use a civil program as a cover for developing weapons. Iran denies any such aim and says it only wants to generate nuclear energy.

Iran's semiofficial Fars news agency quoted Salehi as saying that some nuclear personnel had access to information about Iran's plans for foreign purchases and commercial affairs. The report did not elaborate on the precise nature of the information or the timeframe over which the spying took place.

"Now, these routes have been blocked. The possibility of information leaking is almost impossible now," Salehi was quoted as saying.

"Our colleagues were awakened. ... The personnel and managers have all reached the conclusion that this is a national issue and that we should ... resolve our problems among ourselves."

Salehi is also the head of the Atomic Energy Organization of Iran. His predecessor as nuclear chief had said more than two years ago that some of the nation's nuclear scientists had been approached by the West but did not accept offers to spy.

Saturday's revelation was the first public word that some personnel have engaged in espionage. With the announcement, Iran appears to be trying to raise public awareness about what it says are plots by the U.S. and its allies to derail Iran's nuclear activities.

Salehi said access to information has been restricted within nuclear facilities as part of the increased security measures.

"In the past, personnel had easy access to information but it is not the case anymore now," Fars quoted him as saying.

Salehi said Iran's nuclear agency also published booklets for its personnel alerting them to the various techniques the West uses to try to lure them into espionage. The booklets spell out "precautionary measures to protect [information] and the life of scientists," he was quoted as saying.

"The issue of spies existed in the past but now we see that it is fading day by day."

When nuclear scientist Shahram Amiri returned home in July from the United States, Iran feted him as a national hero and said he in fact acted as a double agent and provided valuable information about the CIA.

American authorities claimed Amiri willingly defected to the U.S. but changed his mind and decided to return home without the $5 million he had been paid for what a U.S. official described as significant information about his country's disputed nuclear program.

Iran said he was kidnapped by American agents in May 2009 while on a pilgrimage to holy Muslim sites in Saudi Arabia. Upon Amiri's return, Tehran portrayed the affair as an intelligence battle with the CIA that it asserted it had won.

More recently, nuclear intrigue has fallen on a complex computer worm that has swept through industrial sites in Iran and was also found on the personal laptops of several employees at Iran's first nuclear power plant.

The malicious computer code, known as Stuxnet, was designed to take over industrial sites like Iran's Bushehr nuclear plant and has also emerged in India, Indonesia and the U.S. But it has spread the most in Iran.

On Tuesday, Foreign Ministry spokesman Ramin Mehmanparast said Iran believed the computer worm was part of a Western plot to sabotage its nuclear program.

Who created the Stuxnet code and what its precise target is, if any, remains a mystery.

The web security firm Symantec Corp. has said Stuxnet was likely spawned by a government or a well-funded private group. It was apparently constructed by a small team of as many as five to 10 highly educated and well-funded hackers, Symantec says.

As Iran battled the computer worm over recent weeks, the intelligence minister announced authorities had arrested two nuclear spies. He did not, however, reveal their identities or clearly link them to the Stuxnet problem.