ISTANBUL - Parliament's decision to strip a jailed opposition lawmaker of his seat is "null and void", Turkey's Constitutional Court has ruled, prompting calls by his lawyer and the opposition for his release and return to the assembly.

Can Atalay was sentenced in 2022 after being convicted of trying to overthrow the government by allegedly organising the nationwide Gezi Park protests in 2013 with philanthropist Osman Kavala, also now jailed, and six others. All deny the charges.

In January, parliament stripped Atalay of his seat following a judicial ruling. Atalay, 48, was elected to parliament in May last year to represent the Workers' Party of Turkey (TIP) while serving an 18-year prison sentence.

The Constitutional Court had ruled in October that the imprisonment of the elected lawmaker violated his rights to security, liberty and the right to be elected.

A detailed ruling by the court, published in Turkey's Official Gazette on Thursday, said the decision of the Court of Cassation not to implement the higher court's October judgment had no legal value.

"Can Atalay should be released and sworn in as an MP. All his rights should be restored," Ozgur Ozel, leader of the main opposition Republican People's Party (CHP), said on Thursday in a post on X.

Atalay's lawyer Deniz Ozen told Reuters the Constitutional Court ruling stated that keeping the lawmaker in prison and stripping Atalay of his status as deputy was not legal.

"The court's ruling paves the way for his release," he said, adding that Istanbul's 13th Criminal Court would make the final decision.

Turkey's Constitutional Court ruled twice, in October and December, that Atalay's imprisonment violated his right to be elected. But the Court of Cassation's refusal to release him on both occasions stoked a judicial crisis.

  - Reuters