The United States and Israel jointly developed computer virus known as "Flame" targeting Iran's nuclear ability, the Washington Post reported on Wednesday.

U.S. officials said the massive piece of malware nicknamed Flame secretly mapped and monitored Iran's computer networks, sending back a steady stream of intelligence to prepare for a cyber warfare campaign, according to the report.

U.S. National Security Agency, the CIA and Israel's military were reported to involve in the efforts that included the use of destructive software such as the Stuxnet virus to cause malfunctions in Iran's nuclear enrichment equipment, said the paper.

One former high-ranking U.S. intelligence official told the Washington Post that both Flame and Stuxnet were elements of a broader assault that continues today, in which cyber-collection against the Iranian program is way "further down the road than this."

The collaboration on Flame, which came to light last month after Iran detected a series of cyberattacks on its oil industry, between the United States and Iran has not been previously confirmed. The virus was believed to be developed at least five years ago as part of a classified effort codenamed Olympic Games, said officials and experts familiar with U.S. cyber operations.

Spokesman for the CIA, the NSA and the Office of the Director of National Intelligence declined to comment on the report.

The Washington Post's story marked the latest of a series of report on U.S. stepped-up cyberattacks overseas.

The New York Times reported earlier this month that U.S. President Barack Obama ordered stepped-up cyberattacks on Iran's nuclear program months after taking office, significantly expanding America's first sustained use of cyberweapons.

The program, launched by the Bush administration and code-named Olympic Games, targets the computer systems that run Iran's main nuclear enrichment facilities, the paper said.

However, a programming error allowed the worm, Stuxnet, which was developed by the United States and Israel, to escape Iran's Natanz plant and go around the world on the Internet in the summer of 2010.

U.S. lawmakers have been enraged by the reports, saying such information should never be leaked to the press and out in the open.

Obama has strongly denied the charges by his political rivals that the White House purposely leaked classified information for political gains in the election year. The Justice Department launched investigations into the possible unauthorized disclosures of classified information by government employees.

In May, Iran's media reported that Iranian cyber experts detected and contained a complicated Israeli spy virus, known as "Flame" that had targeted Iran's oil industry.P The head of Information Technology Organization of Iran, Ali Hakim Javadi, said earlier that the country's experts had managed to produce anti-virus software that could spot and remove the detected computer virus "Flame."

Over the past few years Iran had been the target of numerous cyber attacks, which had been carried out to disrupt the country's industrial systems.