A recent deadly explosion at a missile base in Iran caused major devastation and will take much longer to repair than a top Iranian general has predicted, according to an analysis of new satellite photos of the site.

In commercial satellite photos released by a private Washington institute, the sprawling compound west of Tehran looks decimated, with buildings seriously damaged or completely wiped out from the November 12 explosion.

"The entire facility was essentially destroyed," said Paul Brannan, a senior analyst at the Institute for Science and International Security (ISIS), which posted the images this week.

"It looks like almost half of the buildings are gone and what's left are the skeletons of the buildings. I would call that a complete destruction of the facility," Brannan, who wrote an analysis of the pictures, told AFP on Wednesday.

Media reports said at least 36 members of the country's Revolutionary Guards were killed in the explosion, including a key figure in Iran's ballistic missile program, Major General Hassan Moqaddam.

Despite speculation the incident may have been a covert Israeli or US-backed attack, the Revolutionary Guards have repeatedly said the blast that rocked the base in Bid Ganeh was an accident.

The chief of staff of Iran's armed forces, General Hassan Firouzabadi, has said the base was being used for the production of an unspecified "experimental product" that could be used against the United States or Israel.

Firouzabadi said the development of the project had been delayed by two weeks because of the explosion, but the satellite images suggested otherwise.

"I would doubt that significantly," Brannan said of the military chief's estimate. "The place was destroyed. You'd have to rebuild it completely. Two weeks is way too short for that."

But Brannan said it was plausible the explosion could have been the result of an accident and that rocket fuel when ignited poses a serious danger.

Brannan said the center of the explosion looks to have been located at what appears to be a crater about 15 meters (yards) wide at the blast site, he said.

On the ISIS website, Brannan wrote that about the same number of trucks were visible in photos after the blast as in images two months earlier.

"Thus, most of the damage seen in the November 22, 2011 image likely resulted from the explosion," he wrote.

It was unclear how the blast would affect Iran's ballistic missile program, which the United States believes is part of an effort to develop nuclear weapons.

The explosion follows a series of setbacks for Iran's nuclear project that are widely suspected to be the result of sabotage, amid speculation Israel and the United States are behind the campaign.

Prominent scientists in Iran's nuclear program have been targeted for assassination and the Stuxnet computer worm reportedly wreaked havoc on industrial equipment for Iran's uranium enrichment work.

Analysts say the Americans favor sanctions along with covert action to disrupt and delay the Iranian nuclear program instead of military action that Washington fears could trigger a wider regional war.

Tensions between Iran and the West have escalated amid a push for fresh sanctions and after Iranian protesters overran the British embassy and another diplomatic compound in Tehran on Tuesday.