An explosion has rocked a busy suburb in southern Beirut that is known to be a Hezbollah stronghold, killing at least four people and injuring 35 more.

Tuesday's car bomb attack at 11.10am local time - claimed by the Nusra Front in Lebanon - was the second blast in less than a month in Shia-dominated Haret Hreik. 

Marwan Charbel, caretaker interior minister, said he had information that the car was packed with explosives and suicide bomber was wearing an explosive belt that did not detonate.

The Nusra Front confirmed in a statement on Twitter that the explosion was a suicide 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," the group said.

The explosion, which was just metres from the site of a blast on January 2, ignited a library on Al-Arid street and was close to other government and residential buildings.

"This is a very targeted area of Beirut, it has been struck four times since the summer," Al Jazeera's Nisreen El-Shamayleh said, reporting from the scene.

"It is a very busy area, very residential and the people who live here are supporters of Hezbollah."

Lebanon's state media quoted a security official as saying the vehicle, a Kia 4x4, was stolen and the owner identified it.

Escalating tensions

The involvement of the Shia Hezbollah group in the Syria conflict has resulted in violence spilling over the border into Lebanon's capital city.

Al Jazeera's Zeina Khodr, reporting from Montreux where Syria peace talks are due to begin on Wednesday, said Syria has been a divisive issue in Lebanon for some time.

"When you speak to people they say that they expect these attacks, and many continue to support the Hezbollah stance. This conflict is no longer confined to the borders of Syria and it is becoming more difficult to control," she said.

"There is an urgency in Beirut, it is a city on the brink and it is becoming increasingly sectarian."

Source: Al Jazeera and agencies