A Turkish court has approved the indictment for “crimes against the state” of a former Turkish president who came to power in a military coup.

The state-run Anatolia news agency reported Tuesday the court accepted the indictment of Kenan Evren, as well as a co-conspirator in the coup, former air force chief Tahsin Sahinkaya.

The ruling brings them closer to standing trial for crimes related to a 1980 military coup. Prosecutors have been seeking life in prison for both men.

Mr. Evren led the coup before serving as Turkey's president until 1989. Calls for him to stand trial began after constitutional amendments passed in 2010 lifted immunity for the coup leaders.

Meanwhile, Turkish media reports say prosecutors have asked that parliamentary immunity for the country's main opposition leader, Kemal Kilicdaroglu, be lifted so he can be investigated for critical remarks that prosecutors say undermine the fair trial process. Kilicdaroglu on Tuesday challenged prosecutors to do so, saying “Lift my immunity.”

On Friday, he questioned the impartiality of the justice system after the arrest of a former army chief and, in November, he described the prison where the suspected coup plotters are being held as “a concentration camp.”

Mr. Evren, who is 94 years old, and Sahinkaya, who is 86, are the only other living members of Mr. Evren's military junta.

The coup leaders were initially hailed as heroes, but subsequently resorted to torture, disappearances and restricting freedom.

The 1980 coup was the third in Turkey's history, although authorities have been investigating what they say was a 2003 military plot to overthrow the Islamic-rooted government of Prime Minister Recep Tayyip Erdogan.

On Friday, Turkish authorities arrested retired General Ilker Basbug over the alleged plot known as Ergenekon, a secularist network the government alleges was planning bombings and other attacks to discredit the government and trigger a military coup.

Turkish media reports last week said Basbug was called to answer questions in connection with a trial of current and former officers linked to Ergenekon.

Turkish authorities have detained more than 300 people including journalists, academics and politicians as part of a wide-reaching investigation into Ergenekon.