Three suspects have been accused of the killings, with prosecutors seeking aggravated life sentences, the Hurriyet daily reported Wednesday, quoting from the prosecutors’ indictment.

In the document, the prosecutors said Russia was waging a war against Chechen opposition leaders who had fled to other countries as well as Chechen groups within Turkey.

Two of the suspects, both Russian citizens, are still on the run. They worked for Russia’s Federal Security Service (FSB) and entered Turkey with fake passports under the names Alexander Zharkov and Nadim Ayupov, the indictment said.

The pair are accused of shooting dead three Chechens on an Istanbul street in 2011, and of the 2009 murder of Ali Osaev — the Istanbul representative of the Caucasus Emirate, designated as a terrorist organisation by Russia and the United States

The third defendant, Temur Makhauri, is a Georgian citizen currently in custody in an Istanbul prison. He only stands accused of Osaev’s murder, with prosecutors alleging he attended his victim’s funeral ceremony after killing him.

Makhauri is also said to have met with FSB agents in Istanbul prior to the murder, according to the indictment.

The first hearing of the trial is scheduled for March 3.

The Kremlin has been fighting insurgents in the North Caucasus since the 1991 collapse of the Soviet Union, waging a war in 1994-1996 against separatist rebels in Chechnya.

After a second war in Chechnya in 1999, the rebellion’s inspiration moved towards Islam with the aim of imposing an Islamic state in the region.

Although the war ended in 2000, rebels have waged an increasingly deadly insurgency, with the unrest spreading into other areas of the North Caucasus.

Turkey, which sought to beef up its influence in the Caucasus following the Soviet breakup, has long been known for being Chechen-friendly.

The suspicion of Moscow’s hand in the four murders has been fanned by local media reports that the weapons used were allegedly of the type favoured by Russian intelligence.