ISTANBUL (REUTERS) - A vehicle exploded near a military facility in Turkey's biggest city of Istanbul on Thursday, wounding seven people, the local mayor said, the latest in a spate of bombings this year.

The explosion hit Istanbul's Sancaktepe neighbourhood, near a military airfield on the Asian side of the city and well removed from its historic centre.

The blast, which sent a large plume of black smoke up over the streets, hit around 5pm local time (10pm Singapore time), when military personnel usually leave the facility to go home, broadcaster CNN Turk said.

"Our citizens are being treated at the hospital. Seven people have light injuries due to shattered glass, six of them soldiers, one civilian," Sancaktepe mayor Ismail Erdem told CNN Turk.

Turkey has been hit by a series of bombings this year, including two suicide bombings 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.

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

The Kurdistan Freedom Hawks (TAK), an offshoot of the outlawed Kurdistan Workers Party (PKK) militant group, has claimed responsibility for two other car bombings this year, both of them in Ankara.

The first, a car bomb that targeted soldiers, killed 29 people in February. The second, at a transport hub a month later, killed at least 37.

TAK says it split from the PKK, which has waged a three-decade insurgency against the Turkish state, but experts who study the militant groups say they retain close links.