Report: Airstrikes in Iraq and Syria kill 459 civilians, 15,000 militants

US-led airstrikes targeting the Islamic State group in Iraq and Syria have likely killed at least 459 civilians and more than 15,000 militants in the past year, a report by an independent monitoring group said on Monday.

The report by Airwars, a project aimed at tracking the international airstrikes targeting the extremists, said it believed 57 specific strikes killed civilians and caused 48 suspected "friendly fire" deaths.

While Airwars noted the difficulty of verifying information in territory held by the IS group, which has kidnapped journalists and activists, other groups have reported similar casualties from the US-led airstrikes.