BEIRUT -- The Lebanese government has confirmed the identity of one of the suicide bombers responsible for a deadly attack on the Iranian Embassy in Beirut as a follower of a firebrand Sunni preacher, a judicial official said on Saturday.

The suspect's link to Sheik Ahmad al-Assir, known for his fiery sermons denouncing Iran's Lebanese Shiite ally Hezbollah, is likely to increase already taut tensions between the country's two largest Muslim sects.

Mouin Abu Daher was initially suspected after his father told authorities that he believed his son was one of the bombers, the official said. Officials said they Friday that they had provisionally identified him.

Investigators from Lebanon's military courts matched Abu Daher's DNA to his father's, the official said. He spoke on condition of anonymity because he wasn't allowed to release the information.

The Tuesday attack targeted the Iranian Embassy in an upscale Shiite-dominated neighbourhood of the Lebanese capital, killing 23 people.

An al Qaeda-linked group, the Lebanese Abdullah Azzam Brigades, claimed responsibility for the attack, one of the deadliest in a series of attacks targeting Hezbollah and Shiite strongholds in Lebanon in recent months.

They said it was payback for the military support that Iran and Hezbollah provide to the Syrian government of Bashar Assad against the mainly Sunni rebels fighting to overthrow his rule.

The killed included a 54-year-old Iranian diplomat, Ibrahim Ansari, who oversaw regional cultural activities.

The Syrian conflict, in its third year, also has become a confrontation between regional powers, chiefly Iran and Saudi Arabia.

It has also created tensions in Lebanon over Hezbollah's open participation in the conflict to shore up Assad forces.

That has deepened sectarian tensions in Lebanon between Sunnis, who tend to support rebels, and Shiites, who tend to support Assad.

The charismatic Sheik al-Assir and his hard-line supporters battled Lebanese soldiers, supported by Hezbollah fighters, in days of clashes in July. Security officials say the preacher is at large, having eluded attempts by Lebanese officials to arrest him.

The SITE Intelligence Group which monitors jihadi threats said Abu Daher was a fan of hard-line al Qaeda linked websites and vowed he would die in a suicide bombing. They published a photo claimed to be Abu Daher, showing a young muscular man with a bushy beard and black cap characteristic of hard-liners.