US-backed forces in Syria announced on Saturday that they have liberated the last area held by the Islamic State of Iraq and the Levant (ISIS) in the eastern Syrian village of Baghouz, declaring victory over the extremist group and the end of its self-declared Islamic caliphate.

"Syrian Democratic Forces declare total elimination of the so-called caliphate and 100 per cent territorial defeat of IS. On this unique day, we commemorate thousands of martyrs whose efforts made the victory possible," tweeted Mustafa Bali, a spokesman for the Kurdish-led Syrian Democratic Forces, referring to the group by its Arabic acronym.