An al-Qaeda linked group fighting against the Syrian government has claimed responsibility for a suicide car bombing last week in a Shiite-dominated south Beirut neighborhood.

The Islamic State of Iraq and the Levant made the claim on Saturday in a statement posted onto a website page used by Sunni militants. It said that it had penetrated the “security system of the Party of Satan [Hezbollah]… and crush its strongholds… in a first small payment from the heavy account that is awaiting those wicked criminals,” according to a translation by AFP.

There was no independent confirmation of their claim, but AFP quoted the Lebanese military saying that DNA evidence linked a man from northern Lebanon to the attack.

ISIL is one of the strongest rebel groups fighting against Syrian President Bashar Assad and controls large swaths of the country’s east. According to Reuters, an alliance of other Syrian rebel groups battled against ISIL in northwest Syria on Friday and Saturday, leaving dozens dead.

Syria analyst Aymenn al-Tamimi noted that while ISIL has launched mortars into Lebanon from near the Syrian border, it’s implausible that it was capable of striking deep into Hezbollah territory.

At least five people were killed in the Thursday attack, the latest in a wave of attacks to hit Lebanon in recent months as Syria’s civil war spills into its smaller neighbor. In late December, a car bomb killed former Sunni minister and ambassador to the US Mohammad Chatah, an outspoken critic of Hezbollah.

The violence has targeted both Sunni and Shiites, further stoking sectarian tensions that are already running high as each community in Lebanon line up with their Syrian brethren on opposing sides of the war. Hezbollah has sent thousands of fighters to Syria to fight alongside Assad’s troops.

The al-Qaeda linked group is battling to impose their extreme version of Islamic law in the region.