Details added (first version posted at 11:57)
Six people have been killed and at least 100 injured after two explosions hit a southern area of the Lebanese capital Beirut on Wednesday, according to Lebanon's health ministry, Al Arabiya reported.
The al-Qaeda linked Sunni extremist group Abdullah Azzam Bridages have claimed responsibility for the twin attacks on its Twitter account.
"The brothers of the Abdullah Azzam Brigades, of the Hussein bin Ali Brigades claim the attack against the Iranian cultural centre, which was a double martyrdom operation," the group's Twitter account said.
The blast, which used 160kg of explosives, hit near the Kuwaiti embassy and 20 meters (yards) from the Iranian Cultural Chancellery in Beirut.
Blast walls were set up in front of the Iranian cultural center recently apparently for fear of such attacks. The Iranian ambassador in Lebanon said the dead included a Lebanese policeman who had been guarding the cultural center, but none of its staff were wounded.
The explosion also occurred near an orphanage run by an Islamic charity, blowing out the building's windows. While children were reportedly included in the casualties, it was unconfirmed if they were from the orphanage.
Prime Minister Tammam Salam, whose Cabinet was formed on Saturday, said the blast is "a message by forces of terrorism to continue in their plan to spread death in Lebanon."
"We got the message and we will respond to it with solidarity and our commitment to peace," he said.
Beirut's southern suburbs, a stronghold of the militant movement Hezbollah, have been hit by seven bomb attacks since July, the most recent of which occurred on Feb. 3.
Wednesday's attack marks the second time an Iranian property has been targeted. In November, a pair of suicide bombings at the Iranian embassy killed at least 25 people, including a diplomat.
Making clear its targets were intentional, the Abdullah Azzam Brigades said its statement via Twitter that "The attack on the Iranian cultural center is a response to the fighting by the Party of Iran (Hezbollah) side by side with the criminal regime in Syria."
Iran is a major backer of Hezbollah. Both are allies with Syrian President Bashar al-Assad.
The series of attacks are linked to the civil war in neighboring Syria with Syrian rebels vowing to strike against Hezbollah in retaliation for its participating in the war.
Hezbollah leader Sayyed Nasrallah on Sunday said his group would continue to fight in Syria, describing Hezbollah's involvement there as necessary to stop the spread of radical Sunni militancy.
Abdullah Azzam Brigades also expressed its staunch pursuit of targeting Hezbollah strong holds in its statement following Wednesday's attack.
"We will continue, with God's strength, to target Iran and its party in Lebanon ... to achieve our two just demands: One, getting the fighters of the Party of Iran out of Syria; Two: releasing our prisoners from the oppressive Lebanese prisons."
The Syrian war has deeply divided Lebanon along sectarian lines and helped fuel a surge in violence that has rattled the already fragile country.