A teenage drug dealer who concocted a "fantasy" of lies after being caught with up to £13,000 of crack cocaine and heroin was today convicted of possession with intent to supply.

Sonny Mannion was caught by police after a passer-by saw him dealing drugs to a man in Portland Road, Summertown, in March.

When he spotted officers approaching, the 17-year-old threw a bag containing 56 wraps of heroin - worth up to £1,400 - into nearby bushes.

Police later searched his flat in Banbury Road and found a further £4,120 of crack cocaine and £7,590 of heroin.

Mannion, who has a string of previous convictions including three robberies, criminal damage, battery, shoplifting and possession of cannabis, had denied two charges of possessing class A drugs with intent to supply.

He told the court he had been kidnapped by three men who had held him hostage for two months, while supplying him with food and cannabis, and made him help deal the drugs to pay off a £130 debt.

The teenager said the men - who he knew only as Rex, Tee and Locks - had grabbed him in East Oxford and pulled him into their car because he had not paid for cannabis he had bought off them a few months earlier.

Mannion said the gang told him they had a gun and threatened to shoot his mother and Bully, his Staffordshire Bull Terrier, if he did not follow their instructions.

Referring to Mannion's claims in his closing speech, Nigel Daly, prosecuting, said: "It's a world of fantasy. It's absolute nonsense.

"He may have got the stash of drugs from these people, but there was no coercion involved."

Remanding Mannion in custody, Judge Christopher Compston said: "I am singularly unimpressed. It seems here is a young criminal hell-bent on being one.

"I think you are a criminal straight through and through. You have been found guilty of a very serious offence. It is because of people like you that this city and the whole of the country is flooded with drugs."

Judge Compston adjourned sentencing to allow pre-sentence and psychological reports to be written.

Speaking after the case, Dc Gerry Holford said: "We found a significant amount of drugs on him and in his property.

"So much, that it would have made him a significant and important dealer in Oxford - particularly in North Oxford.

"It is a shame somebody so young has got into drug dealing at this age.

"A lot of dealers start their career in their late teens. For somebody of Mannion's age to be caught with this amount is unusual but it is not unusual for someone to be in drug dealing at that age."

Police spokesman Toby Shergold added: "It is a real result for the neighbourhood teams in North Oxford."