A rebel alliance in southern Syria has begun an offensive against government forces in Quneitra province, near the Israeli-occupied Golan Heights.
A spokesman for the Southern Front said groups fighting in the operation had signed a pact, which did not involve the al-Qaeda-affiliated al-Nusra Front.
The area around the town of Quneitra came under heavy bombardment on Wednesday morning, Reuters reported.
Smoke could be seen rising from the area and small arms fire was heard.
Later, sirens sounded at two Israeli settlements in the Golan Heights.