A teenage boy with a degenerative disease lived the last months of his life in agonising pain because of delays at Great Ormond Street Hospital, a health watchdog has found.

Arvind Jain, 13, who suffered from Duchenne muscular dystrophy, died in August 2009 after waiting months for an operation.

The Parliamentary and Health Service Ombudsman's report in to the circumstances surrounding Arvind's death said he "suffered considerable distress and discomfort".

In January 2009, Arvind's con- dition had deteriorated so much that he struggled with swallowing and eating. His consultant paediatric neurologist recommended an operation that would allow Arvind to feed through his stomach, but "chaotic and substandard" referral procedures led to further delays.

Months later, Arvind's condition worsened to the point that he was not well enough to operate on. He died in August 2009.

The report criticised the care provided to Arvind as "far below the applicable standards as to amount to service failure".

The ombudsman wrote: "Witnessing Arvind's deterioration knowing that more could be done to provide him with a feeding operation significantly distressed his family and has continued to distress them following Arvind's death."

Arvind's sister Shushma told the BBC: "To read that he was suffering all the time, that was disgusting. He had been asking us repeatedly if he would get the operation."

Medical director of Great Ormond Street Hospital, Professor Martin Elliot, said: "We apologise unreservedly to Arvind's family. We let him down in failings of clinical care."