The Syrian government and opposition activists say troops backed by Russian airstrikes are pressing ahead with an assault against rebels in central and northern Syria.

The fighting is particularly intense in the central Homs province, with a fresh offensive announced Friday in the northern Aleppo province. The offensives on multiple fronts appear to be aimed at stretching rebel lines and keeping the insurgents off balance.

The Syrian Observatory for Human Rights said around 42 people were killed in airstrikes and fighting in Homs province. The Local Coordination Committees, an activist network that follows the war, put the number at 57.

Russia began its air campaign Sept. 30, and Syrian troops and allied militiamen launched an ambitious ground offensive a week later.