TRIPOLI, Libya — Libya's official news agency says unidentified militants assassinated a senior Libyan judge in an eastern city known to be a stronghold of Islamic militants.

LANA quoted the head of the Court of Cassation in Green Mountain province, Abdel-Aziz al-Trabilsi, as saying Judge Mohammed Naguib was shot dead in a drive-by shooting in front of the courthouse.

The killing took place in the eastern city of Derna, known to be dominated by hardline Islamic militias such as Ansar al-Shariah, which is suspected to have been behind the Sept. 11 attack on the U.S. mission in Benghazi.

The violence underscores the instability that has rocked Libya after the overthrow and killing of longtime dictator Moammar Gadhafi.