A British aircraft took part in the air strike in Syria which led to the deaths of dozens of regime soldiers and has threatened to scupper the recent deal against Isis between the US and Russia.

It is believed that a UK Reaper drone was part of the American-led raid on Dayr az Zawr last Saturday

A Ministry of Defence spokesman said: “We can confirm that the UK participated in the recent coalition air strike in Syria south of Dayr az Zawr on Saturday and we are fully cooperating with the coalition investigation. The UK would not intentionally target Syrian military units. It would not be appropriate to comment further at this stage.”

The admission comes on the eve of the second anniversary of Operation Shader – Britain joining the American-led coalition’s bombing campaign against Isis which initially focused on Iraq. The Cameron Government’s decision to extend the mission to Syria caused deep divisions in the country and bitter exchanges during a Commons debate.

The Iraqi government had invited the Western coalition to take part in military action against Isis; no such authorisation had come from the regime of Bashar al-Assad in Damascus and opponents questioned the legality of the mission.

Despite Mr Cameron’s assertion that the strikes needed to include Syria to “crush the head of the snake”, subsequent British air strikes in Syria have been extremely limited in numbers, with just 12 per cent taking place in Syria with the rest focusing on Iraq.

In pictures: Aleppo bombing Show all 14 1 /14 In pictures: Aleppo bombing In pictures: Aleppo bombing Bombing in Aleppo Smoke rises after airstrikes on the rebel-held al-Sakhour neighborhood of Aleppo, Syria April 29, 2016. Reuters In pictures: Aleppo bombing Bombing in Aleppo A Syrian family runs for cover amid the rubble of destroyed buildings following a reported air strike on the rebel-held neighbourhood of Al-Qatarji in the northern Syrian city of Aleppo, on April 29, 2016. AFP/Getty Images In pictures: Aleppo bombing Bombing in Aleppo A man reacts as he stands on blood stains at a site hit by airstrikes in the rebel held area of Aleppo's al-Fardous district, Syria, April 29, 2016. Reuters In pictures: Aleppo bombing Bombing in Aleppo The damage of the airstrikes in the rebel-held area of Aleppo on April 28 Reuters In pictures: Aleppo bombing Bombing in Aleppo The damaged the Medecins Sans Frontieres (MSF)-backed al-Quds hospital after it was hit by airstrikes, in a rebel-held area of Syria's Aleppo Reuters In pictures: Aleppo bombing Bombing in Aleppo Syrians evacuate an injured man amid the rubble of destroyed buildings following an air strike on a rebel-held of Aleppo on April 29, 2016. AFP/Getty Images In pictures: Aleppo bombing Bombing in Aleppo People inspect the damage at a site hit by airstrikes, in the rebel-held area of Aleppo's Bustan al-Qasr AP In pictures: Aleppo bombing Bombing in Aleppo A man leads a woman in tears and child out of the scene after airstrikes hit Aleppo AP In pictures: Aleppo bombing Bombing in Aleppo Civil defence members search for survivors after an airstrike at a field hospital in the rebel held area of al-Sukari district of Aleppo Reuters In pictures: Aleppo bombing Bombing in Aleppo A Syrian boy is comforted as he cries next to the body of a relative who died in a reported air strike in the rebel-held neighbourhood of al-Soukour in the northern city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo A Syrian family walks amid the rubble of destroyed buildings following a reported air strike in the Bustan al-Qasr rebel-held district of the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrian civil defence volunteers and rescuers remove a baby from under the rubble of a destroyed building following a reported air strike on the rebel-held neighbourhood of al-Kalasa in the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrians help a wounded youth following an air strike on the Fardous rebel held neighbourhood of the northern Syrian city of Aleppo Getty Images In pictures: Aleppo bombing Bombing in Aleppo Syrian civil defence volunteers evacuate people from a damaged building following a reported airstrike in the rebel-held neighbourhood of Tareeq al-Bab in the northern city of Aleppo

Vladimir Putin ordered Russian air strikes in Syria last year. There were accusations from the Syrian opposition and its Western backers, including Britain, that Moscow’s strikes were targeting “moderate” rebels as well as Isis.

A deal between the US secretary of state, John Kerry, and the Russian defence minister, Sergei Lavrov, was supposed to coordinate the air strikes, but the attack on Dayr az Zawr came days later, leading to a furious reaction from Moscow.

Damaged trucks carrying aid, in Aleppo (AP)

The Pentagon stressed that it had stopped the mission as soon as the Russians sent information that regime soldiers and vehicles may have been hit and expressed “regret” at the loss of lives.

A vest of the Syrian Arab Red Crescent hanging on a damaged vehicle, in Aleppo (AP)

However, at an emergency meeting of the UN Security Council on Saturday night, Russia accused the US of jeopardising the Syria deal. The US ambassador to the United Nations, Samantha Power, responded: “Russia really needs to stop the cheap point scoring and the grandstanding and the stunts and focus on what matters, which is implementation of something we negotiated in good faith with them.”