A boy reacts in a site hit by what activists said were airstrikes carried out by the Russian air force in the town of Douma, Syria Jan. 10, 2016.

Russian airstrikes on Syria have killed nearly 1,400 civilians since Moscow started its aerial campaign nearly four months ago, a group monitoring the war said on Saturday.

The Britain-based Syrian Observatory for Human Rights, which collects information from a network of sources on the ground, said the Russian strikes had also killed 965 ISIS fighters as well as 1,233 fighters from various other insurgent groups.

The main Syrian opposition group heading to Geneva peace talks on Saturday has demanded a halt to a joint Russian and Syrian bombing campaign they say targets mostly civilians in rebel held areas as a pre-condition for engaging in talks with the Syrian government.

Russia began a major aerial campaign on Sept. 30 to help its ally Syrian President Bashar al Assad. The airstrikes tilted the war in Assad’s way after major setbacks earlier in 2015 brought rebel groups close to the coastal heartland of his Alawite sect.

Moscow says it is targeting ISIS militants but rebels and residents say the Russian air strikes are causing hundreds of civilian casualties in indiscriminate bombing of civilian areas away from the frontline.

Related articles across the web

• Russian Air Strikes Target Syrian Rebels' Diesel Fuel Market
• US brings ambitious Syria peace plan to UN
• Caption Contest: Kerry, Putin, Lavrov Staring Match Edition
• Syria army retakes key hilltop in coastal province
• Caption Contest: Kerry, Putin, Lavrov Staring Match Edition
• Netherlands hits back at "completely absurd" Assad assertions
• Russia open to Assad's ouster after Syria transition, diplomats
• Russia reported open to Assad's ouster
• Hollande: Destruction of Islamic State is common goal of France, Russia