Turkey's Constitutional Court has ruled that the lengthy jailing of a former head of the pro-PKK People's Democracy Party (HDP) violated his rights, a decision published in the Official Gazette on Friday showed, but he was not expected to be released due to a separate investigation.

Selahattin Demirtaş has been in jail since 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. It also ordered compensation of TL 50,000 ($7,300) be paid.

However, media reports said the ruling would not lead to his release due to a separate investigation and arrest order.

Demirtaş was detained in November 2016 along with other top figures of the HDP on terror charges after they refused to attend trials related to earlier cases they were accused in. He and his party are often criticized for their open support of the terrorist group PKK, which is responsible for the killings of thousands since the early 1980s.

He was sentenced to four years and eight months in jail for carrying out terrorist propaganda in a speech in 2013. In 2016, he was also sentenced for insulting "the Republic of Turkey, the Turkish nation, the Turkish state and state institutions."

The most serious charges he is facing are related to the notorious Kobani riots on Oct. 6-7, 2014, and the role of HDP-linked officials and municipalities in the PKK terrorist group's unilateral move to end the reconciliation period and launch an unprecedented barricade and trench attacks in cities and towns in Turkey's southeast.

A court ruled last September that Demirtaş should be released while his main trial continues. The Constitutional Court ruling concerns the detention for this period.

Prosecutors then launched a new investigation and requested his arrest again after the lifting of the previous detention order. Demirtaş denies the charges against him.