Two suicide bombings rocked Iran's embassy compound in Lebanon on Tuesday, killing at least 23 people including an Iranian cultural attache and hurling bodies and burning wreckage across a debris-strewn street.

A Lebanon-based Al Qaeda-linked group, the Abdullah Azzam Brigades, claimed responsibility and threatened further attacks unless Iran withdraw forces from Syria, where they have backed President Bashar Al-Assad's 2-1/2-year-old war against rebels.

Security camera footage showed a man in an explosives belt rushing towards the outer wall of the embassy before blowing himself up, Lebanese officials said. They said a car bomb parked two buildings away from the compound had caused the second, deadlier explosion. The Lebanese army, however, said both blasts were suicide attacks.

In a Twitter post, Sheikh Sirajeddine Zuraiqat, the religious guide of the Abdullah Azzam Brigades, said the group had carried out the attack. "It was a double martyrdom operation by two of the Sunni heroes of Lebanon," he wrote.

Lebanon has suffered a series of sectarian clashes and bomb attacks on Sunni and Shi'ite Muslim targets which have been linked to the Syrian conflict and which had already killed scores of people this year.

Tuesday's bombing took place on the eve of more talks between world powers and Iran over Tehran's disputed nuclear programme. They came close to agreeing an interim deal during negotiations earlier this month.

The bombs also struck as Assad's forces extended their military gains in Syria before peace talks which the United Nations hopes to convene in mid-December and which Iran says it is ready to attend.

CULTURAL ATTACHE KILLED

"At one entrance of the Iranian embassy I counted six bodies outside," Reuters television cameraman Issam Abdullah said. "I saw body parts...thrown two streets away. There is huge damage."

The embassy's sturdy metal gate was twisted by the blasts, which Lebanon's Health Minister Ali Hassan Khalil said killed 23 people and wounded 146.

An Iranian Foreign Ministry spokeswoman said the bombs were "an inhuman and vicious act perpetrated by Israel and its terror agents", Iran's Irna news agency reported.

Israeli lawmaker Tzachi Hanegbi said his country had played no role. "The bloodshed in Beirut is a result of Hezbollah's involvement in the Syria crisis. Israel was not involved in the past and was not involved here," he said in Jerusalem. - Reuters