Over two-thirds of the parliament approved the first clause of the controversial bill on Friday, which is a high enough level of support to allow the authorities to change the constitution.

However, the assembly was due to hold two more votes on the bill later in the day.

Under the current regulation, lawmakers have a right to full immunity from prosecution. If the bill passes, some 138 deputies would lose that right, including 101 from the pro-Kurdish HDP and the main opposition CHP party.

Turkish president Erdogan has accused the HDP of links with Kurdish militants waging an insurgency in Turkey.

Less competition for Erdogan

The HDP, which has 59 deputies, claims that the majority of them could end up in jail, mostly for over public statements that might be interpreted as verbal support for the insurgents.

In this way, the ruling AKP could all but wipe out the pro-Kurdish faction, eliminating the third-biggest party in the Turkish parliament.

The bill already sparked a massive brawl on the floor of the assembly earlier this month.

Government critics claim the move serves to consolidate Erdogan's grip on power, with the HDP accusing the president of waging a "totalitarian attack" against their party.

Germany responds to vote

Spokesman for German chancellor Angela Merkel, Steffen Seibert, said that representation of all groups in Turkey was important for inner stability.

"The increasing polarization of the domestic political debate in Turkey fills us with concern," he said.

Merkel intends to broach this topic when meeting Erdogan next Monday, Seibert added.

dj/kl (Reuters, AFP, dpa)