ISTANBUL (Reuters) - Prosecutors in Istanbul have concluded that an attack on the city's second airport two weeks ago that killed an aircraft cleaner was caused by mortar fire, local media reported on Thursday.
Four mortar rounds were fired from around 2 km (1.2 miles) away from the airport in the Dec. 23 attack, the state-run Anadolu Agency said, citing the state prosecutor's office on the Asian side of Istanbul where the airport is located.
The attack at Sabiha Gokcen, which handles both domestic and international flights and is owned by Malaysia Airports, fatally wounded a cleaner on a plane belonging to budget carrier Pegasus.
Turkey has stepped up security at its international airports as it has tried to prevent foreign fighters, hidden among the millions of tourists who visit each year, seeking to cross its territory and join the ranks of Islamic State in Syria.
There has been no suggestion, however, that Islamist militants were behind the Sabiha Gokcen attack.
A Kurdish militant group once linked to the outlawed Kurdistan Workers Party (PKK), which has fought a three-decade insurgency for greater autonomy in Turkey's southeast, claimed responsibility several days later.
The Kurdistan Freedom Hawks has in the past claimed some attacks outside the PKK's regular area of operation in the mainly Kurdish southeast, such as a 2012 assault on a military bus that killed two soldiers in a coastal resort town.
The Anadolu Agency said prosecutors had not yet concluded who was responsible for the airport attack and that investigations were continuing.