ANKARA: Turkey will not be deterred from its operations inside Syria after a suspected Syrian army helicopter bombed and killed Turkish-backed rebels, Foreign Minister Mevlut Cavusoglu said on Wednesday.

The attack late on Tuesday killed two rebels and wounded five others, the Turkish military said, in what appeared to be the first direct clash with Syrian forces since Turkey launched a cross-border incursion in August.

Forces loyal to President Bashar al-Assad continue to bomb Syrian rebels instead of Islamic State, Cavusoglu told reporters at a news conference. But Turkish military operations to clear its border of Islamic State will continue until the forces it backs take the Syrian city of al-Bab, he added.

Cavusoglu also said Turkey will take measures if there is an attack against the Iraqi city of Tal Afar. A largely Iranian-trained Shi'ite paramilitary force said last week it would back Iraqi government forces advancing towards Tal Afar, about 55 km (34 miles) west of Mosul.

Turkey fears the use of Shi'ite militias in the U.S.-backed offensive on Mosul, Islamic State's last major stronghold in Iraq, will trigger sectarian strife in the mainly Sunni region and trigger an exodus of refugees.