BEIRU: Syrian rebels pressed on with a fresh advance in the central province of Hama, as they bid to take out its military airport, a rebel commander and an activist group said Tuesday.

"The rebels are now nine kilometers away from Hama military airport, which they want to put out of action," said Syrian Observatory for Human Rights director Rami Abdel-Rahman.

A rebel leader in the area, who gave his name as Hassan, said Hama military airport was important because "that is where the regime makes its barrel bombs, and warplanes take off from there to carry out airstrikes on (opposition-held) areas across Syria."

Barrel bombs have killed hundreds of civilians, especially in rebel areas of the divided northern city of Aleppo, in recent months.

According to the Observatory, rebels and their Al-Qaeda ally, the Nusra Front, took over a major checkpoint north of Hama city, which is firmly under regime control, Monday night.

The takeover of the checkpoint at Tarabih comes on the back of Sunday's capture of a weapons depot in the area.

"The regime has suffered several defeats in Hama province in recent days," said Abdel-Rahman.

As they have advanced, rebels have cut off the road linking Hama city, the provincial capital, to a string of regime-controlled Christian and Alawite villages in the west of the province, he added.

According to Hassan, the regime is sending reinforcements.

"They are stepping up their troop presence here, which will limit the regime's capabilities in other areas, such as Aleppo," said the rebel commander, who spoke to AFP via the Internet.

As for the military airport: "We are already striking it with Grad missiles," said Hassan.

The air force has used deadly barrel bombs, which are being manufactured in Hama military airport, to strike opposition-controlled areas across Syria for many months.

In Aleppo alone, airstrikes including barrel bomb attacks have since December killed hundreds of civilians including children, and forced thousands of families to flee, as the regime has unleashed a massive aerial offensive there.

Rights groups have hit out at the regime for its use of barrel bombs, which they describe as failing to discriminate betweeen civilian and military targets.

Syria's war has killed more than 170,000 people and forced nearly half the population to flee their homes.