Updated

A security official says a leading Libyan activist and vocal critic of the country's Islamists has been shot dead in a drive-by shooting in the city of Benghazi.

Security official Mohammed al-Hegazi said gunmen in a grey sedan stopped AbdulSalam al-Musmari on his way home after Friday prayers and shot him at close range.

Al-Hegazi said an investigation into the motives behind the attack and who committed the killing is under way.

Al-Musmari was a leading lawyer who headed a group credited with launching the 2011 protests against the country's longtime dictator Moammar Gadhafi. Al-Musmari also was a vocal critic of the country's Muslim Brotherhood group, which wields significant political and financial clout in post-Gadhafi politics.