British Air Force Typhoon fighter aircraft have operated alongside France's air force in a joint strike on an underground arms cache in Syria used by the IS group, according to the UK Ministry of Defence.
The site, identified by intelligence, was assessed as storing arms and explosives, the statement said, and was situated in mountainous terrain just to the north of the historic site of Palmyra in central Syria.
"Our fighter planes utilized Paveway IV guided bombs to target a several entry passages leading to the facility... preliminary assessments indicate the target was engaged successfully," the MoD said.
There was no indication of any civilian impact in the operation conducted Saturday night and every plane involved returned safely, the defence officials confirmed.
The Typhoon FGR4s were supported by a Voyager refuelling tanker.
IS - alternatively referred to as ISIS - established militant control over significant areas in Iraq and Syria until 2019.
"This strike underscores British leadership, and determination to operate in unison with our partners, to eradicate any re-emergence of IS and their violent and radical beliefs in the region," the British Defence Secretary John Healey remarked.
UK warplanes have conducted surveillance missions over Syria to "prevent any efforts to regroup" of the group following its routing at the climactic battle in Baghuz in 2019, the ministry said.
"I must thank every member of our armed forces who took part in this strike for their professionalism and their valour," he said. "They were part of a great many British personnel deployed over the holidays. This mission, to take out terrorist threats who threaten our security, shows how British military are ready to step up, all year round, keeping Britain secure domestically and influential overseas."
During December, the US military conducted what it described as a "large-scale strike" on Islamic State objectives in the country, following an ambush killed two US servicemembers and a local interpreter in the Palmyra area.
The United Nations reports IS still has between 5,000 and 7,000 militants in Iraq and Syria.
