ANKARA, Turkey (AP) — Turkey has ordered predominantly Kurdish Syrian militants to withdraw east of the Euphrates river "immediately" or face more strikes by Turkish forces that crossed the border last week.

Foreign Minister Mevlut Cavusoglu spoke Monday, as Syrian opposition groups reported that Turkish-backed Syrian rebels have captured more towns and villages in northern Syria.

Turkish tanks rolled across the border last week to help Syrian rebels seize the town of Jarablus from the Islamic State group, a move that was also aimed at deterring further advances by Kurdish-led forces.

The Britain-based Syrian Observatory for Human Rights says the rebels have captured 21 towns and villages near Jarablus from the U.S.-backed and Kurdish-led Syria Democratic Forces.

The Local Coordination Committees, an activist collective, says the rebels captured seven more villages since late Sunday.