A Syrian activist group said government air raids have killed nearly 2,000 civilians this year in and around Aleppo, the country's largest city.
The Syrian Observatory for Human Rights said Friday 567 children and 283 women were among those killed in the northern city, which is a stronghold for opposition fighters.
The figure, which relies on the Britain-based group's contacts with activists and others on the ground, amounts to 14 civilians killed each day between January 1 and May 29.
The Observatory's Rami Abd al-Rahman says the ongoing violence makes it impossible to hold free and fair presidential elections on June 3, as planned.
"You are going to election for president and you are killing your people, and you're killing civilian people, and you're killing around 600 children these last few months in one area? They say now we can go to a democratic election? You should go directly to court and they should send you to jail," said al-Rahman.
More than 150,000 people have been killed in Syria's civil war, which erupted three years ago after President Bashar al-Assad responded with force to protests against his rule.
Fighting has been particularly intense in Aleppo, which is divided between government and rebel forces.
Government airplanes and helicopters began an intense bombing campaign in December, often using crude barrel bombs that cause indiscriminate destruction and have been condemned by rights groups.