BEIRUT, Lebanon - Syrian aircraft pummeled opposition areas in the northern city of Aleppo on Sunday, killing at least 32 people and extending the government's furious aerial bombardment of the rebel-held half of the divided city to an eighth consecutive day.

Since it began Dec. 15, the government's unusually heavy air campaign in Aleppo has killed more than 200, smashed residential buildings, and overwhelmed hospitals with casualties. The timing of the assault - a month ahead of planned peace talks in Switzerland - suggests President Bashar al-Assad could be trying to strengthen his position and expose the opposition's weaknesses before sitting down at the negotiating table.

Sunday's air raids targeted several Aleppo neighborhoods, but the worst hit was Masaken Hanano, where bombs fell on a secondhand market, a two-story building, and a main road, activists said.

The Aleppo Media Center activist group said at least 32 people were killed, and published a list of the names of the dead on its Facebook page. Another group, the Britain-based Syrian Observatory for Human Rights, said in a later statement that at least 47 people, including seven rebels, were killed.

"The medics say they are removing people in parts; they aren't sure how many there are," said Hassoun Abu Faisal, with the Aleppo Media Center.

Activists said the strikes were carried out by government helicopters that dropped so-called barrel bombs, crude devices filled with explosives and fuel that are wildly inaccurate but cause massive damage on impact.

Human-rights groups warn that even if Syrian forces are targeting rebels with the bombs, they often explode in residential areas, killing civilians.

The raids have exacted a devastating toll. Over the first four days, the air strikes killed at least 189 people and wounded 879, according to the aid group Doctors Without Borders.

Communities in the surrounding countryside also have been hit.

Schools decided to close Monday in opposition-held parts of Aleppo to avoid more casualties, citing attacks in Marea, north of Aleppo, the Aleppo Media Center reported.

Syrian officials have not commented on the air raids.