Gunmen shot dead a Libyan colonel, the latest in a string of attacks targeting security forces by armed groups who are looking to challenge to central government control.

Wednesday's attack in Benghazi killed Col Salih Al Houdheiry from the Libyan Marines force.

"He was driving his car with his son when he was targeted," said a senior Libyan security source. "Many bullets penetrated his body, he died immediately, while his son is in intensive care with a gunshot wound to the head."

Houdheiry was dropping off his son at the Benghazi medical school when the attack took place, security service spokesman Abdullah al-Zayedi told the AFP news agency, adding that the officer's son was seriously wounded and is in intensive care.

On Sunday, an air force officer was killed when a bomb was attached to his vehicle in Benghazi, while a colonel working for the Libyan intelligence was gunned down in front of his house as he left for work in the city.

A police patrol was also targeted in an rocket-propelled grenade attack at one of the main entrances to the city, though no injuries were reported, security sources said.

Benghazi, the cradle of the 2011 uprising that ousted former dictator Moamer Kadhafi, has seen a series of assassinations targeting officers in the security services.

Other attacks have targeted Western interests and diplomats, and much of the violence, including the killing of the US ambassador last year, has been attributed to radical armed groups in the region.

Libya's fledgling government has been struggling to build up an effective army and police force since Kadhafi's overthrow. 

To help maintain security, Libya's government relies on militias made up of thousands of Libyans who took up arms against Gaddafi. But these rival groups have often involved into security threats themselves.

An OPEC country, Libya is also struggling to put an end to protests and strikes by oil facility guards and armed activists that have crippled crude operations in the east. Production is now at 700,000 barrels per day, less than half the usual output.

Source: Agencies