Turkish warplanes struck Kurdish militant targets in northern Iraq on Wednesday, killing six militants, the military said in a statement, as part of a widening campaign against the outlawed Kurdistan Workers Party (PKK).

The statement said the air strikes targeted the Zap region, the Turkish name for a river which flows across the Turkish-Iraqi border and is known as Zab in Iraq.

On Tuesday, Turkish planes bombed Kurdish militants in Iraq's Sinjar region and northeast Syria, killing around 70 militants inside the two neighbouring states, according to a Turkish military statement.

Designated a terrorist group by Turkey, the United States and the European Union, the PKK has waged a three-decade insurgency against the Turkish state for Kurdish autonomy. More than 40,000 people have been killed in the conflict, most of them Kurds.