Britain's Ministry of Defence has said that Royal Air Force Typhoon jets joined French aircraft in a joint strike on an underground weapons facility used by the Islamic State group (IS) in Syria.
The statement said that following "careful" intelligence analysis, officials believed the facility contained weapons and explosives, and was located in the mountains just north of Palmyra, an ancient site in central Syria.
"Our aircraft used Paveway IV guided bombs to target several access tunnels leading to the facility... Initial indications are that the target was successfully struck," the Ministry of Defence said.
The Ministry of Defence added that there were no indications of any civilian casualties in the attack, which took place late on Saturday, and all aircraft returned safely.
A detailed assessment of the strikes is being carried out, but officials believe the "target was successfully struck".
IS had imposed its jihadist rule over parts of Syria and Iraq until 2019.
UK Defence Secretary John Healey said: "This action demonstrates our UK leadership and our unwavering resolve to stand shoulder to shoulder with our allies to eliminate any resurgence of Daesh and their dangerous and violent ideologies in the Middle East."
The ministry said that RAF aircraft have been patrolling over Syria since the defeat of IS in the Battle of Baghuz in 2019 to "prevent any potential resurgence".
Healey added: "I want to thank all members of our armed forces involved in this operation for their professionalism and their courage.
"They were among the thousands of British personnel deployed over Christmas and New Year. This operation, which is about eliminating dangerous terrorists who threaten our way of life, shows how our armed forces remain ready all year round, keeping Britain safe at home and strong abroad." The RAF has been using drones and manned aircraft to attack IS fighters and targets as part of the international coalition since 2014.
The United Nations says IS still has between 5,000 and 7,000 fighters in Syria and Iraq.
In November, Syria – under its new president, Ahmed al-Shara – became the 90th country to join the US-led coalition fighting the group.
Officials say the coalition's goal is to eliminate the remaining elements of the so-called Islamic State and stem the flow of foreign fighters into the Middle East. Last month, after two US soldiers and a civilian translator were killed in an attack in Palmyra, the US military launched what it called a "major strike" against IS targets in Syria.
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