A woman was killed and another wounded after an explosion of unknown origin on Wednesday at Istanbul’s second international airport.

A woman was killed and another wounded after an explosion of unknown origin on Wednesday at Istanbul's second international airport, Turkish television reports said.

Airport cleaner Zehra Yamac, 30, died of head wounds hours after the blast on the tarmac at Sabiha Gokcen airport on the Asian side of Turkey's largest city, CNN-Turk and NTV television reported.

The explosion took place just outside the terminal building where planes park for their passengers to embark and disembark.

Turkey's private carrier Pegasus Airlines said in a statement the explosion took place next to one of its planes on the tarmac while the two cleaners were nearby.

"There were no passengers either on the plane or on the stairway. Sabiha Gokcen airport is continuing its normal operations," Pegasus said.

The wounded victim was also a cleaner. Yamac was hospitalised but died of her wounds.

Sabiha Gokcen airport, named after Turkey's first female fighter pilot, is the second international airport in Istanbul after Ataturk Airport on the European side of the city.