BEIRUT (AFP) - Four people were killed in an apparent suicide car bombing in south Beirut on Tuesday, in the latest in a string of attacks targeting strongholds of Lebanon's Shiite movement Hezbollah.

The blast was quickly claimed by Al-Nusra Front in Lebanon, a group believed to be linked to Al-Qaeda's Syrian arm, which said it was a suicide attack.

"Four people are dead, and there are 35 injured," Red Cross spokesman Ayad al-Monzer told AFP.

The official National News Agency said the attack appeared to be a suicide bombing.

"Body parts apparently belonging to a suicide bomber were at the scene," it said.

Al-Nusra Front in Lebanon posted a statement on its Twitter account, saying it was behind the attack.

"With the help of God almighty we have responded to the massacres carried out by the party of Iran (Hezbollah)... with a martyrdom operation in their backyard in the southern (Beirut) suburbs," it said.

The blast took place on the busy Al-Arid Street in the Haret Hreik neighbourhood, which had been targeted by a suicide car bombing in early January.

An AFP photographer saw troops and Hezbollah security men deployed as firemen worked to put out the flames and health workers took the injured to hospitals.

The blast is the sixth in a string targeting areas considered strongholds of Hezbollah since the group announced it was sending fighters to support President Bashar al-Assad's troops in neighbouring Syria.

It is the third to hit the group's strongholds in a month.

Less than a week ago, a car bomb exploded in Hermel in the eastern Bekaa valley, killing three people. That attack was also claimed by Al-Nusra Front in Lebanon.

And on Jan 2, a suicide car bombing claimed by the jihadist Islamic State of Iraq and the Levant hit the street targeted on Tuesday, killing five people.

While the attacks appear to be targeting the powerful Hezbollah, those killed have all been civilians.