Police raided the homes of suspects in 11 provinces as part of an investigation against the outlawed Kurdistan Workers' Party (PKK) and its off-shoots in urban centres, the source said on condition of anonymity.

It was the third operation this year. More than 100 people have already been charged in the investigation carried out by the chief prosecutor's office in Diyarbakir, the largest city in Turkey's mainly Kurdish southeast.

Among those detained on Thursday were eight mayors from Kurdish-majority towns, who used to be members of the now-defunct Democratic Society Party (DTP).

The DTP was banned by Turkey's top court two weeks ago on the grounds that it was linked to the PKK, a verdict that sparked violent Kurdish protests across the southeast that claimed two lives.

Following the ban on the DTP, party members have joined the Peace and Democracy Party, a recently founded Kurdish party.

The PKK, listed as a terrorist group by Ankara and much of the international community, took up arms for Kurdish self-rule in the southeast in 1984, sparking a conflict that has claimed some 45,000 lives.

Since August, the Ankara government has been working on a plan to expand Kurdish freedoms in the hope of ending the PKK's deadly campaign.