BEIRUT - Syria's army backed by heavy Russian air strikes clashed with rebels holding a town on a supply route close to the border with Jordan on Wednesday as part of a major government assault to try and regain southern territory, rebels and residents said.
Rebels from an array of groups - some of them backed by Western powers - fought back against the offensive near a former air base north of the town of Sheikh Maskin, insurgents at the scene told Reuters.
"The army is making progress with heavy Russian aerial bombing. The raids are not stopping we have had over 40 raids in the last 24 hours alone," said Abu Alaa al-Haurani, a commander in a-Failaq al Awal, part of the Southern Front of Western-backed rebels.
The army offensive towards Sheikh Maskin is part of the government's first major assault in southern Syria since Russia joined the fight on Sept. 30 to support its ally President Bashar Assad.
Russia, which did not confirm the strikes and has up to now concentrated on the northwest and coastal areas, has said it is primarily targeting hardline Islamic State fighters.
Washington and other regional powers have regularly accused it of striking other anti-Assad rebel groups, seen as more moderate, that the some in the West hope will form part of a future settlement of the near five-year war.
The army took the Brigade 82 base from the rebels on Tuesday, lost it as bad weather set in, they took it once more overnight with the support of the air strikes, said rebels.
Syria's army said it had made advances overnight against insurgents it said were mainly al-Qaida inspired groups.
Sheikh Maskin, the main goal of the army's southern campaign, lies on one of the main supply routes from the capital Damascus to the city of Deraa, close to the border with Jordan.
The recapture of Sheikh Maskin, located at the heart of Deraa province, would consolidate the army's hold over the heavily fortified region which has formed a southern line of defense protecting Damascus.
Rebels from another mainstream anti-Assad armed opposition alongside some Islamist groups said they shelled army posts in the city of Izraa, a main government held town that has major fortifications and is based to the east of Sheikh Maskin.
Activists and residents say Russian air strikes, in which missiles and bombs are launched from high altitude, are distinct from Syrian air force strikes which rely more on untreated barrel bombs dropped from helicopters flying at lesser height.