Lebanese soldiers took over security checkpoints manned by Hezbollah in the party's eastern stronghold of Baalbek Sunday, a day after a Shiite-Sunni shootout killed four people, a Hezbollah source said.

It was the second time this week that Hezbollah has handed control of its checkpoints to the army, after the military also deployed in the southern suburbs of Beirut.

"We have handed over to the Lebanese army our checkpoints at the entrances and in the centre of the city," a Hezbollah source told AFP on condition of anonymity.

"We are now working on handing over other checkpoints, until the military takes control of them all and it becomes responsible for security."

Hezbollah set up its own security checkpoints in areas it controls after bombings that wounded more than 50 people on July 9 and killed 27 on August 15.

Militants were deployed for weeks to search vehicles and check people's identity cards.

Sunday's handover comes a day after four people, including two Hezbollah fighters, were killed in a clash with Sunni gunmen in Baalbek.

A fifth man, a Lebanese soldier, died Sunday after being wounded during the clash.

It was not immediately clear what triggered the fighting at the Hezbollah-manned checkpoint.

"We were preparing to hand over the checkpoints to the army before yesterday's incident, but the incident delayed the handover by a day," said the Hezbollah source.

An AFP correspondent in Baalbek said Hezbollah militants have withdrawn from the checkpoints, and that the city was calm despite Saturday's firefight.

Hezbollah is a powerful force, particularly in the southern suburbs of Beirut and eastern and southern Lebanon, where it has been accused of running a "state-within-a-state".

Hezbollah, whose military wing was blacklisted by the European Union in July, did not disarm at the end of the 1975-1990 civil war, arguing that it needed to protect Lebanon from Israel.

It is backed by Iran and is a staunch supporter of the embattled regime of Syrian President Bashar al-Assad.

Hezbollah has found itself targeted in Lebanon over its involvement in Syria, where its fighters have battled alongside Assad's forces against rebels seeking to topple him.

The group's involvement has divided opinion in Lebanon, where many Shiites back the regime and many Sunnis support the Sunni-dominated uprising.