Akcakale (Reuters) - Rebels tore down a Syrian flag at a border gate on the Turkish frontier on Wednesday as they fought for control of the crossing, and schools on the Turkish side shut as bullets flew into Syria's northern neighbour.

Television footage showed Syrian rebels taking down the Syrian flag on top of a government building at the Tel Abyad border gate. Sporadic gunfire could be heard and black smoke rose from parts of what appeared to be a customs building.

Turkish officials were unable to confirm whether the rebels, fighting to overthrow Syrian President Bashar al-Assad, had seized control of the whole crossing, and said Assad's forces might send in reinforcements at any time.

There was no sign of any government troops at the crossing from television pictures broadcast live on CNN Turk.

The fighting, which started late on Tuesday, looked to be the first attempt by insurgents to assert their grip over a border zone in Syria's al-Raqqa province, most of which has remained solidly pro-Assad.