A 23-year-old soldier who was killed when a US Apache helicopter fired on a British base in Afghanistan died as a result of "mistaken beliefs and cumulative failures", a coroner has ruled.

Lance Corporal Christopher Roney, from Sunderland, died from head injuries at Patrol Base Almas in Sangin on December 21 2009.

After a five-day hearing, Sunderland Coroner Derek Winter listed a series of errors made leading up to the tragedy.

He ruled: "L/Cpl Christopher Roney died as a consequence of assumptions made, mistaken beliefs and cumulative failures by friendly forces to appropriately assess the totality of their situational awareness in respect of the ongoing events at and in the vicinity of Patrol Base Almas on December 21 2009. The deployment and use by friendly forces of attack helicopters was done in circumstances that ought to have been assessed by them to conclude sooner than they did that their target was not an enemy force and that the attack should be aborted."

L/Cpl Roney, of 3rd Battalion The Rifles, died from head injuries he suffered while manning a position at Patrol Base Almas, in Sangin, Helmand, on December 21 2009.

As night fell, the base was rocked by a huge Taliban bomb and the platoon based there were fighting off an attack when, without their knowledge, two US gunships were called in to help. But one fired 200 rounds into the base - despite the flagpole, machine gun, barbed wire and men in uniform - as the air crews believed it was an enemy position and carried out two strafing runs.

There was harrowing evidence from soldiers on the ground, who could not understand where the devastating onslaught was coming from. Senior British Army staff - not based in Almas - liaised with the Apaches and mistakes were made when the crews were given a series of grid references and told there were no friendly forces in the vicinity. There was also confusion over pictures relayed from two cameras - one of which was mounted on an unmanned drone.

Statements from the four unnamed pilots and co-pilots were read out during the inquest. The coroner heard tales of heroism as comrades raced to help the seven badly injured soldiers - the most serious casualty being L/Cpl Roney, who was married to Lorna and whose son William was then five months old. He was flown to Camp Bastion but could not survive his terrible injuries and died the next day.

It is believed injured soldiers could sue the Ministry of Defence for negligence. Mr Winter said at the start of the inquest that no one will face prosecution for the friendly fire incident. The coroner said lessons must be learned and he will write to the Defence Secretary with recommendations.

An MoD spokesman said: "Our thoughts remain with the family and friends of Lance Corporal Christopher Roney. This tragic incident occurred in a highly challenging and fast-moving operational environment. All of those involved acted with the best intentions to assist their comrades, but tragically mistakes were made. Comprehensive investigations have been conducted and key lessons identified. Processes have been updated, training has been enhanced and patrol base mapping has been improved. The Army and MoD will now also closely study the coroner's findings as part of our commitment to ensure all possible lessons are learned."