Turkey is hoping for a breakthrough in efforts to end a four-decade insurgency by Kurdish militants after their jailed leader welcomed calls by the government to find a political solution to the conflict.

Abdullah ?calan, founder of the banned Kurdistan Workers party (PKK), told opposition lawmakers visiting his prison on an island south of Istanbul over the weekend that he was willing to support a “new paradigm” aimed at a settlement after peace talks collapsed into fierce fighting in 2015. ?calan is 25 years into a life sentence for treason and separatism.

The visit followed a surprise offer in October from Devlet Bah?eli, the leader of the government’s nationalist governing partner, to free ?calan in return for ordering the PKK to lay down arms. President Recep Tayyip Erdo?an has called the proposal a “historic window of opportunity”.