Istanbul airport explosion: Kurdish militant group claims responsibility - and says more attacks are on the way

Turkish police search around Sabiha Gokcen Airport after an explosion left one dead and extensive damage to planes on 23 Decenber 2015. (EPA)

A Kurdish militant group has claimed responsibility for an attack at Istanbul's second airport that killed a cleaner, and threatened more assaults.

The Kurdistan Freedom Falcons - an offshoot of the Kurdistan Workers' Party, or PKK - said in a statement on its website that it attacked Sabiha Gokcen International Airport with mortar guns.

It said the December 23 attack was in retaliation for the Turkish government's stepped-up military operations against the PKK.

Authorities have not disclosed the cause of the pre-dawn explosion at the airport, which also injured another cleaner and damaged three planes, saying it is still under investigation.

Turkish security forces last week launched a large-scale operation to rout militants linked to the PKK in mostly Kurdish districts.

More than 180 rebels were killed.

AP