Baladi News
The US-backed Syrian Democratic Forces (SDF) say they have liberated the last area held by so-called Islamic State in the eastern village of Baghouz.
The UK and US, along with other coalition partners, have been supporting the fight against IS for the last four years.
Following the announcement, the Prime Minister Theresa May said: "The liberation of the last Daesh-held territory wouldn't have been possible without the immense courage of UK military and our allies."
"We will continue to do what is necessary to protect the British people, our Allies and partners from the threat Daesh poses," she added.
The battle to capture Baghouz has lasted for weeks with civilians fleeing the area.
The UK is the second largest contributor in the coalition against IS, behind the US, with British jets flying missions from RAF Akrotiri in Cyprus.
Operation Shader began in September 2014 with air strikes over Iraq and extended to Syria the following year.
The RAF campaign has killed and injured an estimated 4,315 members of IS, according to figures released by the Ministry of Defence.
Source: Forces Network.