Four people have been killed in a suicide bomb attack in a residential neighbourhood of southern Beirut.

It was not immediately clear what the blast had targeted.

The explosion went off on a busy street of small shops and restaurants in the Haret Hreik area of Beirut's largely Shia southern suburbs.

At least 20 people were wounded in the attack in the Hezbollah stronghold.

Hezbollah districts in Lebanon have been hit by a string of rocket and bomb attacks claimed by Sunni militants.

Haret Hreik was also the target of a car bomb attack earlier this month that killed at least five people.