Syrian activists say rebels continue to press ahead with their offensive in the southern province of Daraa on the Jordanian border.

A rebel victory there would be significant because it would deprive President Bashar Assad of control over Syria's southern border with Jordan. In the past few months, rebels seized control of much of the western border with Turkey and made significant gains along the eastern border with Iraq.

Rami Abdurrahman, head of the Britain-based Syrian Observatory for Human Rights, says heavy clashes were continuing Sunday at two towns near Daraa.

A Jordanian border official says he is hearing heavy artillery and seeing smoke rising from areas in the province's Yarmouk Valley.

On Saturday, rebels seized several army checkpoints, clearing a 25-kilometer (15-mile) stretch along the Syrian-Jordanian border.