US and Israeli intelligence have collaborated in developing the Stuxnet computer worm aimed at upsetting Iran’s nuclear enrichment program, New York Times reported on Saturday.

The report goes on to add that Israel had tested the effectiveness of the computer malware in its nuclear facility in Dimona Complex in the Negev desert, which is reportedly “the heavily guarded heart of Israel’s never-acknowledged nuclear arms program.”

According to military and intelligence experts, Israel has built nuclear centrifuges identical to those in Iran’s Natanz nuclear plant at Dimona Complex.

New York Times quotes an American expert on nuclear intelligence saying; “To check out the worm, you have to know the machines. The reason the worm has been effective is that the Israelis tried it out.”

Experts have told New York Times that the Stuxnet program “appears to have wiped out roughly a fifth of Iran’s nuclear centrifuges and helped delay, though not destroy, Tehran’s ability to make its first nuclear arms.”

Ali Akbar Salehi, head of Iran’s Atomic Agency has fiercely rejected such claims maintaining that those who claim the virus has passed through the firewall should consider Iran’s nuclear file closed.

“The Stuxnet computer worm has not penetrated the main systems at Bushehr Plant and was only observed in a few personal laptops,” Salehi had said earlier.

Last July, reports of penetration of Stuxnet in Iran’s industrial computer systems and possibility of damage to Iran’s nuclear equipment were published.

Mohammad Liyayi, a ministry of mining and industry official announced that 30 thousand IPs were infected with the Stuxnet worm and added: “The virus is designed for cyber warfare and it transmits abroad information about production lines.”

A computer expert quoted by New York Times maintains however that “code analysis makes it clear that Stuxnet is not about sending a message or proving a concept. It is about destroying its targets with utmost determination in military style.”

Reza Taghipour, Iranian minister of communication and information technology told the media in September that the sources of the Stuxnet infection have been identified and added: “This computer malware wormed its way into industrial systems via flash memories and not through networks.”

Taghipour went on to say however that Iranian computers were no longer facing any threat from Stuxnet.

Recently US and Israeli officials have changed their assessment of Iran’s nuclear status and now claim Iran is years away from developing the capability for building nuclear weapons.

Iran has repeatedly maintained that its nuclear program is peaceful and no aimed at building weapons.