Abu Bakr al-Baghdadi may have been killed in a Russian air strike in Raqqa which took place following intelligence reports that the Isis chief was meeting with commanders to plan the last-ditch defence of the besieged capital of the “caliphate”.

The defence ministry in Moscow confirmed that an attack had been carried out on 28 May after information was received about the meeting. It continued: “According to the information which is now being checked via various channels, present at the meeting was [Isis] leader Abu Bakr al-Baghdadi, who was eliminated at the strike.”

There had been previous reports of the death or wounding of Baghdadi. However, if verified this time, it would be a massive blow to Isis, both symbolically and strategically, with the group now all but driven out of Iraq and clinging on to its territory in Syria. It is likely, Russian and Western military officials believe, to lead to a crumbling of resistance and a rise in the already high number of desertions from the group’s ranks.

Killing Baghdadi will also further raise the prestige of Vladimir Putin, whose sending in of forces to Syria has been widely viewed internationally to be in marked contrast to the indecision and prevarication which has marked the American and European posture in Syria.

The American military, Moscow stressed, was kept fully informed of the operation. Colonel John Dorrian, a spokesman for the US-led coalition in Iraq, said he could not confirm if Baghdadi had been killed. Rex Tillerson, the US Secretary of State, said in March that a large number of the Isis leader’s lieutenants were dead and it was “only a matter of time before Baghdadi himself met the same fate”. There has been no reaction, so far, from Isis outlets or the group’s supporters to the reports.

The 10-minute strike between 12.35 and 12.45 in the morning, by SU-34 and SU-35 warplanes, it is claimed, killed up to half a dozen senior leaders of the group, as many as 30 field commanders and more than 300 fighters who had been brought in to guard the meeting. If confirmed, this means that Isis has lost a major part of its command as its enemies close in on Raqqa from three sides. Among those reported killed were the senior figures Abu-al-Khadzhi al-Mysri, Ibrahim Haef al-Khadi and Suleiman al-Shuauakh, the group’s security chief.

Assaults on Raqqa have been launched by troops of the Assad regime, backed by Russian air strikes and Iranian and Lebanese Hezbollah forces on the ground; a Kurdish and Arab force with US and British special forces and backed by American warplanes; and an Arab and Turkman contingent supported by the Turks.

The Isis meeting in the southern edge of Raqqa, according to Russian officials, was due to discuss plans of delaying the enemy with the use of suicide bombers and IEDs (improvised explosive devices) while escape routes were organised for the leadership.

In pictures: Isis' weapons factories Show all 11 1 /11 In pictures: Isis' weapons factories In pictures: Isis' weapons factories A mortar round fin manufactured by Isis in Gogjali, Mosul, November 2016 Conflict Armament Research In pictures: Isis' weapons factories Isis rocket components discovered in Gogjali, Mosul, Iraq in November 2016 Conflict Armament Research In pictures: Isis' weapons factories Isis mortars discovered near Karamlais, Iraq, in November 2016 CAR In pictures: Isis' weapons factories An Isis rocket launch frame in Qaraqosh, November 2016 Conflict Armament Research In pictures: Isis' weapons factories A memo from Isis' COSQC on quality control at a manufacturing facility in Gogjali, Mosul, November 2016 Conflict Armament Research In pictures: Isis' weapons factories Electrically-operated initiators manufactured by Isis in forces Gogjali, Mosul, November 2016 Conflict Armament Research In pictures: Isis' weapons factories Isis mortar tubes at a manufacturing facility in Karamlais, November 2016 Conflict Armament Research In pictures: Isis' weapons factories An Isis mortar production facility discovered in Gogjali, Mosul, in November 2016 Conflict Armament Research In pictures: Isis' weapons factories An Isis weapons manufacturing facilities near Mosul in November 2016 Conflict Armament Research In pictures: Isis' weapons factories Stocks of French-manufactured Sorbitol, Latvian potassium nitrate and Lebanese sugar at an Isis weapons factory in Iraq Conflict Armament Research In pictures: Isis' weapons factories A destroyed Isis weapons facility in Qaraqosh, Iraq, November 2016 Conflict Armament Research

The only public appearance of Baghdadi took place when he declared the creation of a caliphate during a sermon in Mosul in June 2014. He was believed to have been in the city before Iraqi forces, backed by the Americans, began the offensive to retake the city. Since then his whereabouts have been unknown, with reports that he was hiding in the desert rather than in any urban location.

There have been a number of reports in the past that Baghdadi had either been killed or injured. He was said to have been severely wounded in a US air strike in March 2015 and in May that year Isis threatened retribution for the attempt to kill its leader. Some subsequent terrorist attacks in Europe, it was claimed, were the results of this threat. There were reports in October last year that he and three other senior leaders of the group had been poisoned but had survived. There were also reports in May and June of this year that he had been badly wounded or killed.