* Blast occurs on highway in southern Beirut

* Previous bombings have targeted mostly pro-Hezbollah areas (Adds details from the scene, background)

By Laila Bassam

BEIRUT, Feb 3 (Reuters) - A suicide bomber killed himself and one other person when he detonated explosives in a minibus in southern Beirut on Monday, a Lebanese security source said.

Lebanese television footage showed the chassis of a vehicle with no roof. Smoke rose in the air and debris lay on a street. Body parts, including a head, were on the road.

The target of the attack was not immediately clear. The minibus exploded on a highway in Choueifat, in the south of the capital, which links several parts of the city.

Last month two bombs hit residential areas of Beirut where the Shi'ite militant Hezbollah group has a strong presence.

A bystander said the minibus had been heading in the direction of those areas, which suggested the detonation may have been premature. It was not immediately clear if the bomber had been a passenger or the driver of the vehicle.

A man working at a petrol station near the site of the blast said: "There was glass everywhere. We saw a head. Then the legs landed near the station."

Lebanon is reeling from the fallout of Syria's civil war next door. Hezbollah has sent fighters to support Syrian President Bashar al-Assad against majority Sunni Muslim rebels.

Lebanese and Syrian Sunni militants supportive of the Syrian uprising have targeted Hezbollah areas with attacks, including a bomb attack on Sunday in the northern Shi'ite town of Hermel.

Four car bombs have exploded in Hezbollah's strongholds in southern Beirut since July. A pair of suicide bombings at the Iranian embassy killed at least 25 people, including an Iranian diplomat, in November. (Writing by Oliver Holmes; Editing by Alistair Lyon)

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