Turkish authorities have released a veteran Kurdish politician and mayor in the southeastern province of Mardin held for more than two months as part of a terrorism investigation, sources in his party said on Friday.

Ahmet Turk, 74, was detained on Nov. 21 in a crackdown which saw dozens of elected mayors removed from municipalities in the largely Kurdish southeast over suspected militant links and replaced with state-appointed administrators.

Turk, who was first elected in 1973 to represent Mardin in the national parliament and served as a lawmaker until 2015, is one of the best-known figures in the Kurdish political movement in Turkey and his detention drew widespread criticism.

Sources in his Democratic Regions' Party (DBP) said he had been released because of deteriorating health. There was no immediate comment from the Turkish authorities.

Turkey has been fighting an insurgency by the Kurdish PKK militant group in the southeast for more than three decades.

President Tayyip Erdogan accuses members of the DBP and the larger pro-Kurdish Peoples' Democratic Party (HDP) of links to the PKK, deemed a terrorist organization by the European Union and United States.

The arrest last November of the co-leaders of the HDP, parliament's second-biggest opposition party, along with thousands of its members drew international condemnation.