Turkish warplanes struck 29 Islamic State group's targets in northern Syria on Sunday while four of the radical militants and two Turkish-backed Syrian rebels were killed in clashes on the ground, the Turkish military said on Monday.

The Turkish air force has stepped up its air strikes in Syria in recent days as the rebels it supports close in on al-Bab, an Islamic State-held city which Kurdish-dominated militias have also been trying to take from the militants.