A Turkish Airlines aircraft at Istanbul's main airport was evacuated and searched after a note threatening a bomb attack was found on board on Monday, an airline spokesman said, although it later turned out to be a hoax.

All 134 people, including the crew, who had been on board the flight from Ataturk Airport to the central Turkish city of Kayseri had been evacuated, the spokesman said. Another plane was later arranged for them, he said.

Turkey has suffered a series of suicide bombings in its cities this year, including two attacks in tourist areas of Istanbul blamed on Islamic State and two car bombings in the capital, Ankara, which were claimed by a Kurdish militant group.

Last year an offshoot of the militant Kurdistan Workers Party (PKK) claimed responsibility for a mortar attack at Istanbul's second airport that killed one airport cleaner and injured another.

A Nato member and a candidate to join the European Union, Turkey is participating in the US-led coalition fighting Islamic State in Syria and Iraq, and also battling a militant insurgency in its largely Kurdish southeast region.