Human Rights Watch says it has identified nearly 1,500 sites where the Syrian government has carried out indiscriminate air attacks over the past year using barrel bombs and other improvised weapons.

The human rights group said in a report released Tuesday that the attacks have had "a devastating impact on civilians," killing or injuring thousands of people in rebel-held territory.

Human Rights Watch said that by examining satellite imagery it identified some 450 major damage sites in 10 towns and villages held by rebel groups in Daraa governorate in the south and over 1,000 in Aleppo. It also examined video and photographic evidence and interviewed witnesses to document the attacks.

The rights group urged the Security Council to impose an arms embargo on Syria's government and groups abusing human rights.