The suspects risk terms ranging from 15 years to life in jail for involvement in the Kurdistan Associations Union (KCK), which prosecutors described as a terrorist group that acted as the urban extension of the armed Kurdistan Workers' Party (PKK), according to the charge sheet seen by AFP.

The judicial onslaught came amid mounting unrest in the southeast after the PKK stepped up violence, prompting a harsh military response and dealing a heavy blow on an already fragile government initiative to boost Kurdish freedoms.

Among the suspects was Osman Baydemir, the popular mayor of Diyarbakir, the largest city of the mainly Kurdish southeast and the centre of the investigation. He risks up to 36 years in jail.

Eleven other regional mayors and former lawmaker Hatip Dicle were among the defendants.

The indictment said the KCK recruited militants for the PKK, made all major decisions shaping Kurdish political life such as the selection of candidates for municipal and parliamentary seats, syphoned off money from Kurdish-held local administrations and orchestrated violent street protests.

Turkey's main Kurdish political parties allegedly acted in line with KCK directives and the organisation was said to be as influential as to slap sanctions on those who disobeyed its decisions.

Kurdish mayors were allegedly required to donate to the KCK the two first salaries they received upon election, while municipal employees were required to donate part of their salaries every month.

The indictment said the KCK was headed by an 11-strong board led by Sabri Ok, a senior PKK militant known to be currently based in Europe.

The charges were brought as part of a massive crackdown on Kurdish activists in the southeast since last year, in which a number of weapons were seized.

Of the 151 defendants, 103 are in jail pending trial.

Officials were yet to schedule the first hearing in the case.

The PKK, listed as a terrorist group by Turkey 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.

The army said earlier Friday that 130 PKK militants had been killed inside Turkey and in an air raid on rebel hideouts in neighbouring Iraq since March, adding it had lost 43 personnel.