At least 44 people have been killed and dozens wounded in government airstrikes across Syria, the Syrian Observatory for Human Rights said.

In Deraa, 15 people were killed while 25 others were wounded due to airstrikes on the district of Jassem, in what the Observatory described as a massacre.

"As usual, the regime is striking populated areas in order to make civilian supporters of opposition fighters turn against them," Observatory director Rami Abdel Rahman said.

"Opposition fighters are making steady progress in Deraa province. The vast majority of the west of the province has completely fallen out of government control, and that is where Jassem is located," Abdel Rahman added.

In Aleppo, eight people were killed including two children due to barrel bombs that dropped on a residential neighbourhood named Baydine, resulting in entire blocks being levelled to the ground.

Several others were killed in Douma, Hama, Idlib and Damascus suburbs.

Increased airstrikes in January

The Observatory recorded 931 government airstrikes and 1083 barrel bombs on towns across Syria in the month of January 2015.

At least 271 civilians were killed, including 50 children and 37 women while at least 1000 were wounded.

The regime first used its warplanes in the Syrian war in July 2012.

Syria's uprising started in March 2011 with anti-government protests later turning into a civil war pitting a range of rebel groups against the military.

According to the UN, at least 220,000 people have been killed since the war broke out, while at least nine million others have been displaced.