An American blogger who has frequently published Israeli security secrets has claimed that the Mossad and Iranian opposition group Mujahedin-e Khalq were responsible for the blast at an Iranian missile base on Saturday in which 17 members of the Iranian Revolutionary Guard Corps were killed, including a senior commander.
Richard Silverstone cited an Israeli "with extensive senior political and military experience" as his source.
The blast, at a military base 40km from Tehran, was felt in the capital. The base reportedly stores long-range Shihab missiles capable of hitting Israel.
The senior officer killed in the explosion was General Hassan Tehrani Moqaddam, said to be the senior commander in Iran's missile force. Sixteen people were wounded.
Residents of west Tehran said they thought it had been a low-level earthquake. A thick cloud of smoke rose over the base for hours.
Iranian officials denied that sabotage was involved and said the explosion was the result of an accident which occurred while ammunition was being moved. A Revolutionary Guard spokesman said an investigation was being carried out into the exact cause of the explosion.
Reports in recent weeks regarding a possible Israeli air strike against Iran's nuclear facilities have raised tensions in the region. Israeli Defence Minister Ehud Barak said yesterday that he did not know the cause of the explosion "but may there be many more".
Two years ago, a similar explosion in a military base 483km from Tehran, where Shahab missiles were stored, killed two people. Foreign press reports at the time said the Mossad was behind that explosion. There have been several other unexplained explosions in recent years.
The spy organisation has also been linked to the assassination of several Iranian nuclear scientists and to the introduction of a computer virus, Stuxnet, which derailed Iran's programme for enriching uranium for a period.
Iranian officials acknowledged on Sunday for the first time that a new computer virus, called Duqu, was targeting the computers of firms in the country. The head of Iranian civil defence, Brigadier General Gholamreza Jalali, said Tehran had developed software to thwart the virus and had distributed it to organisations and corporations.
A western security firm, Symantec, has said Duqu is the precursor to a future Stuxnet-like attack.
Silverstone, the blogger, has become a channel for information that is blocked in Israel by the censor but which certain sources in Israel would like to see published.
He was the first to publish the name of the new head of the Mossad and the first to reveal a secret army memo spelling out the rules relating to the Gaza blockade, including specific foods and other items banned.
But he has not always proven correct. Yossi Melman, who writes on security matters in Ha'aretz, has said Silverstein "has transformed himself into the international message board of information which military censorship and Israeli courts forbid publishing".By Abraham Rabinovich