BEIRUT: Syrian government forces Tuesday seized a rebel-held neighborhood on the northwest outskirts of Aleppo, tightening their siege of the opposition-held parts of the city, activists said.

The Britain-based Syrian Observatory for Human Rights said loyalist troops had full control of the Leramun district after heavy clashes, and reported fighting for neighboring Bani Zeid, which is also held by rebels.

The two areas have been used by rebels to launch rockets into government-held districts in the west of the city.

Aleppo has been roughly divided between government control in the west and rebel control in the east since mid-2012.

In recent weeks, government advances around the city's outskirts have severed the only remaining route into the rebel-held eastern neighborhoods, effectively placing them under siege.

Opposition forces have responded by firing barrages of missiles into government districts, killing scores of civilians.

"The importance of capturing Leramun and Bani Zeid is to stop the missile fire and also to further tighten the siege," said Observatory director Rami Abdel Rahman.

He said government forces had now surrounded Bani Zeid, reporting heavy airstrikes in the area and ongoing clashes.

Activists had no immediate toll in the fighting.

Government forces effectively severed the opposition's Castello Road supply route on July 7, when they advanced to within firing range.

They have tightened the encirclement of the rebel-held east since then, taking parts of the road itself and prompting food shortages and spiraling prices in opposition neighborhoods.

Syria's Al-Watan daily, which is close to the government, also reported advances in Leramun, an industrial area that once housed scores of factories.

Government forces have also continued to pound opposition areas of the city, with the toll in barrel bomb attacks Monday in the Al-Mashhad neighborhood rising to 18, the Observatory said.

The group had earlier given a toll of 12.

The dead included two women and a child, as well as a rebel commander who was killed with four members of his family, activists said.

It added that the toll was expected to rise further because bodies were still thought to be trapped under the rubble 24 hours after the devastating attacks.

More than 280,000 people have been killed in Syria since the conflict began in March 2011 with anti-government protests that were met with a government crackdown.