A mortar attack was the cause of a deadly incident on December 23 at Istanbul's Sabiha Gokcen airport that left one person dead and damaged several planes, Turkish prosecutors said on Thursday.
Four mortar shells were fired from a forested area around two kilometres (1.25 miles) from the airport, prosecutors said in a statement carried by the Anatolia news agency.
A Kurdish group calling itself the Freedom Falcons of Kurdistan had claimed the action as revenge for the Turkish army's relentless military campaign in the Kurdish-dominated southeast.
But two weeks after the incident, this was the first official statement confirming an attack.
Airport cleaner Zehra Yamac, 30, died of head wounds while five planes suffered slight damage as a result of fragments from an explosion.
"The investigation has revealed that four mortar shells were fired at around 0215 (0015 GMT) from a wooded area about two kilometres from the airport," the statement said.
"Three of the shells landed on the apron landed next to each other while the other landed on a different area," it said, adding that it was "fragments of shrapnel" from the shells that had hit the nearby planes and the cleaning worker.
It said the forested area was still being examined to determine what the specific target was and who was behind the attack.
The Freedom Falcons of Kurdistan (TAK) said in a statement on December 26 that the airport attack was a response to the "fascist attacks that turn Kurdish cities into ruins."
The attack came as Turkey wages an all-out offensive against the Kurdistan Workers' Party (PKK), with military operations backed by curfews ongoing to flush out the rebels from several southeastern urban centres.
Turkish officials say the TAK is a front for PKK attacks on civilian targets, but the PKK claims TAK is a splinter group over which it has no control.
Sabiha Gokcen airport, on the Asian side of Istanbul, is the second international airport in the city after much larger Ataturk airport on the European side.