Royal Air Force Typhoon jets have conducted a mission with French warplanes in a combined operation on an subterranean weapons facility in Syrian territory operated by the IS group, according to the UK's MoD.
The location, identified by reconnaissance, was believed to be containing munitions and bombs, the release indicated, and was positioned in mountains just to the north of Palmyra in the heart of Syria.
"Our aircraft employed laser-guided Paveway IV weapons to strike a number of access tunnels leading to the site... early reports are that the strike was effective," the MoD said.
There was no indication of any harm to civilians in the operation late on Saturday and each participating jet made a safe return, the MoD added.
The British jets were assisted by a Voyager tanker plane.
The Islamic State group - referred to as the so-called Islamic State - enforced militant control over significant areas in Iraq and Syria until 2019.
"This strike demonstrates the UK's leading role, and commitment to stand shoulder to shoulder with allied nations, to eradicate any re-emergence of the terrorist group and their harmful and extremist ideologies in the Middle East," the British Defence Secretary John Healey remarked.
British military aircraft have conducted patrols over Syrian airspace to "prevent any efforts to regroup" of the group following its defeat at the climactic battle in Baghuz in 2019, the authorities noted.
"I extend gratitude to every member of British forces who took part in this strike for their expertise and their valour," the Defence Secretary said. "Including them were a great many UK service members stationed over Christmas and New Year. This operation, to remove terrorist threats who endanger our security, demonstrates how our armed forces are ready to step up, all year round, ensuring Britain's security at home and influential overseas."
In December, the American forces carried out what it described as a "massive strike" targeting Daesh sites in Syria, following an attack claimed the lives of two US troops and a civilian linguist in Palmyra.
The UN says Islamic State still maintains roughly 5-7 thousand combatants in both countries.
