A drug addict has denied injecting his girlfriend with heroin moments before she overdosed, collapsed and died.

Jason Caswell told a jury how he and Tracey Bradley had both taken the drug but insisted each had administered their own 'fix'.

And Caswell broke down in tears as he said they had only used the residue left over in a spoon from an earlier heroin 'session' with friends at their flat at Wensleydale House, Keighley.

The 29-year-old told Bradford Crown Court: "What was left on the spoon didn't look enough to kill anybody.

''It didn't look more than a £10 bag."

Caswell, now of Hainworth Wood Road, Woodhouse, denies manslaughter and a further charge of administering a noxious substance so as to endanger life.

He told how mum-of-one Miss Bradley, 28, had suffered breathing problems after injecting her arm and had asked him to call an ambulance.

When he returned from the phone box, she had turned blue and had stopped breathing, said Caswell.

He said he had watched others overdose on several occasions and recalled how paramedics had given them adrenaline injections to counter the effects.

John Topham, prosecuting, accused Caswell of telling a nurse how he had injected Miss Bradley and later changing his story when speaking to the police.

Caswell - who had consumed heroin, Temazepam and Valium, said : "By the time I got to the hospital I was in an utter mess because of the drugs I had taken that day. I didn't know what I was saying."

He told the jury: "In the ambulance I kept saying things like 'What have I done?'"

When asked what he meant by this he replied: "I was taking on guilt. It was that I had let her down in the relationship, not that I had done something wrong.''

He added: ''It was that I had not been 100 per cent in helping her get off the heroin."

And Caswell - who the jury heard has convictions for theft, burglary and handling - denied a claim he had been seen injecting Miss Bradley earlier.

Judge Alistair McCallum asked Caswell how addicts knew how strong their batches of heroin were, adding: "You could go to Manningham Lane and get heroin that was eight per cent pure but go to Burnley and get it 60 per cent. Is it all total guesswork?"

Caswell told him: "Yes it is. That is why I would never inject anyone else."

The trial continues.