Stabbing victims and their families last night pleaded for people to put down their knives or face longer jail sentences.

Figures released today revealed almost half of people caught carrying a knife in Oxford were not charged - instead receiving a caution or having no action taken against them.

In the year to March, knives were used in 108 crimes in Oxfordshire, including assaults, sex attacks, street robberies and the killing of Stephen Pinker. Latest figures show one person every three days was caught with a knife in Oxford but only half were charged with possession.

The statistics emerged as 14-year-old stab victim David Idowu became the 19th teenager to meet a violent death in London this year.

Samuel Marriott-Gray, 22, remains in a coma after his attacker Leonard Morrison plunged a knife into his brain almost two years ago outside a party in Blackbird Leys. His mother Sonia McCarthy said anyone caught with a blade should be jailed.

She added: "Given what is happening at the moment there should be stiff penalties.

"Why are they carrying a knife in the first place? If someone is properly punished then they would think twice about carrying a knife a second time.

"If they just get a caution or a fine they can go brag to all their mates that they got away with it."

Becky Holmes, the fiancée of father-of-two Stephen Pinker, who had his throat slashed in an attack outside an Oxford pub, said people who carried knives were cowards.

She said: "I appeal to anyone thinking of going out with a knife to think first about people whose lives they are going to ruin and everyone else who is going to suffer."

Stabbing victim Roy Sinclair added: "There is no point giving someone a caution for carrying a knife. What does that do? People carrying knives should get five years in jail."

Police in Oxford only began counting the number of people stopped for possession of a point or bladed article in April.

Between April 1 and May 31 officers caught 22 people carrying a knife in Oxford.

Eleven were charged, five cautioned and no further action taken against four others. Two more suspects remain on bail.

Oxford commander Supt Brendan O'Dowda said it was not always appropriate to charge someone for possession of a knife because some may have legitimate reasons for carrying a blade while others might have no previous convictions.

He added: "There is no soft option. If someone is found in the street in possession of a knife they will get arrested.

"It's almost unheard of for someone to be cautioned and then get caught again.

"I encourage officers to stop and search anyone they have reason to believe is carrying a knife, but we don't want to demonise youngsters and I don't think we have a knife crime culture which exists in other cities."

In the last year, blades were used in 30 robberies in Oxford and 16 around the county. Criminals also wielded a knife in 24 assaults and sexual offences in Oxford and 35 around Oxfordshire.

Overall, the number of knife crimes in Oxfordshire has fallen from 125 to 108, although police do not know how many people have been stabbed in Oxfordshire in the past year.