ANKARA (Reuters) - Turkey has called for an emergency meeting of NATO to discuss the security situation in Iraq after militants took 80 Turkish citizens hostage during a lightning advance, a Turkish foreign ministry official said.

Sunni insurgents from the Islamic State in Iraq and the Levant (ISIL) overran the city of Tikrit on Wednesday and closed in on Iraq's biggest oil refinery, making further gains against the Shi'ite-led government.

(Reporting by Tulay Karadeniz; Writing by Nick Tattersall; Editing by Hugh Lawson)