"Army units are continuing to progress on several axes in Sheikh Miskeen" state news agency SANA said.

The Syrian Observatory for Human Rights a Britain-based monitor reported heavy fighting and several dozen Russian air strikes on the town.

"Regime forces now control around 70 percent of Sheikh Miskeen" Observatory chief Rami Abdel Rahman said.

The group did not have an immediate casualty toll for in the fighting.

The town is strategically important because of its location on a crossroads between Damascus to the north and the city of Sweida to the east both of which are under government control.

It also lies about 12 kilometres (seven miles) from the rebel stronghold of Nawa another key target for regime forces.

A security source told AFP the town was a "launching pad" for rebel operations and one of the opposition's "centres of gravity for the whole of Daraa province".

He said seizing control of the town would sever a key rebel supply route to areas under opposition control around Damascus.

Last month government troops captured the Brigade 82 base outside the town and they have since been pushing to capture Sheikh Miskeen.

Most of Daraa province is controlled by opposition forces though the government holds parts of the provincial capital and a few villages in the northwest.

Syria's loyalist army has been on the offensive since staunch government ally Russia began an aerial campaign in support of regime forces on September 30.

Since then the regime has recaptured several key rebel towns in coastal Latakia province as well as advancing in the northern province of Aleppo and in Daraa.