One person has been killed and another injured in an explosion at the second largest airport in the Turkish city of Istanbul.
Authorities are investigating whether the blast at the Sabiha Gokcen airport early on December 23 was caused by a bomb or not.
The blast occurred when no passengers were in the area. The casualties were among cleaning staff.
Police tightened security at entrances to the airport after the incident, searching vehicles as a helicopter flew overhead.
Bomb attacks by Kurdish, leftist and Islamist militants are common in Turkey.
A three-decades-old conflict between the state and the militant Kurdistan Workers Party has flared up in Turkey's mainly Kurdish southeast since the collapse of a ceasefire in July.