The most senior reservist SAS officer in Afghanistan has resigned over the death of three of his colleagues and a female Intelligence Corps soldier who were blown up while travelling in a lightly armoured Snatch Land Rover.

Major Sebastian Morley, who commanded 23 SAS, one of two Special Air Service reserve units, is understood to have been disgusted by the death of his comrades who died when their vehicle drove over a landmine in Helmand province on June 17. He is said to have included highly critical comments about equipment in Afghanistan in his resignation letter.

A report in The Daily Telegraph claimed that Major Morley had accused the Ministry of Defence of “gross negligence” and that the failure to supply the right equipment was “cavalier at best, criminal at worst”.

The four who died were Corporal Sarah Bryant of the Intelligence Corps, the first British servicewoman to die in Afghanistan, and three members of 23 SAS, Corporal Sean Reeve and Lance Corporals Richard Larkin and Paul Stout. Defence sources said that the landmine was so huge that it would probably have destroyed a more heavily armoured vehicle.

Major Morley is understood to have blamed chronic underinvestment in equipment for the deaths of the four soldiers. This was denied last night by the MoD, which said that Major Morley had made clear that he had resigned for personal reasons.

The Special Forces’ role in Afghanistan is principally carried out by the Special Boat Service, but the reservist SAS squadron works alongside the SBS.

Major Morley’s decision to stand down is a considerable blow for the Army, especially given the number of highly publicised resignations in recent months. In June Brigadier Ed Butler, former commander of 16 Air Assault Brigade and also a former SAS officer, resigned his commission, stating as his reason a wish to have more time with his family.

Lieutenant-Colonel Stuart Tootal, former commanding officer of the 2nd Battalion The Parachute Regiment, resigned last November, and a former head of 22 SAS, the regular Army Special Forces regiment, resigned last year.

Although there has been widespread criticism of the continuing use of the Snatch Land Rover in Afghanistan, the MoD has announced a £700 million programme to send 700 new armoured vehicles to the country. .

The MoD confirmed that Major Morley had resigned and described the incident on June 17 as a tragedy. A spokesman said: “Equipping our personnel is a clear priority and we are absolutely focused on providing them with a range of vehicles that will protect them from the ever-shifting threats posed by the enemy.”

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