Turkey is reported to have closed its main border crossings into northwest Syria after its troops were attacked by Syrians angered by violence against their countrymen in Turkey.

Turkish police had earlier announced the arrest of nearly 500 people following attacks on Syrian properties and vehicles in several Turkish cities.

The country is now home to more than three million Syrian refugees and tensions with local communities have been growing.

At least four people were killed in the Syrian border city of Afrin in an exchange of fire between Turkish troops and armed protesters. Angry Syrian civilians have also hurled stones at Turkish convoys and tore down Turkish flags.