"[The proposed bill] will have a very negative impact on Turkey, and it is very clear that the attempt to strip MPs of immunity targets us," Demirtas told the Guardian, warning that the proposal puts the personal security of political activists at risk.
In January, a number of HDP legislators who support the Kurds' call for more autonomy in the southeastern Anatolia region were investigated for inciting unrest and circulating terrorist propaganda.
"Democratic political channels in Turkey are already in great difficulty, and if the bill passes, many people will feel that these channels have been shut completely. The belief in democracy and politics of peace will drop to zero," Demirtas said.
The Turkish parliament is due to debate the bill on Tuesday, while a final vote is scheduled for Friday. The official pretext for the AKP-sponsored proposal is that dossiers for lifting of immunity currently affect 138 members of the 550-seat parliament.