Turkey's Constitutional Court has ruled that the lengthy jailing of a former head of Turkey's main pro-Kurdish party violated his rights, a decision published on Friday showed, but he was not expected to be released due to a separate investigation.

Selahattin Demirtas, one of Turkey's best known politicians, has been in jail since November 2016 on terrorism-related charges. He faces a sentence of up to 142 years in jail if found guilty in the main case against him.

The court's decision said his detention had exceeded a reasonable period and his right to freedom had been violated, ordering the payment of compensation.