Video games that glorify gangs and soap operas with violent storylines are leading young people into a life of crime, says a mother whose son was stabbed to death.

Ann Oakes-Odger told a panel of experts in Birmingham led by former Prime Minister's wife Cherie Blair that she believed over-exposure to such images meant many young people lived in a "twilight world" between reality and unreality.

The commission - visiting the five cities in Britain with the worst records for gun and knife crime - also heard of the heartache of West Midlands mother Barbara Sawyers, whose son Daniel Bogle, 19, was shot dead in Smethwick five years ago.

The Birmingham visit comes days after the death of 16-year-old Londoner Jimmy Mizen - the 13th teenager to be killed in the capital this year. Ms Oakes-Odger's 27-year-old son Westley bled to death on a street in Colchester, Essex, after being stabbed in the neck while drawing money from a cashpoint.

Her criticism of video games came days after the launch of the 18-rated Grand Theft Auto IV, which features gangs, guns and street violence.

Last year broadcasting standards watchdog Ofcom rapped the BBC after an episode of EastEnders showed a violent gang attack on the Queen Vic pub involving hammers, bottles and glasses.

"If you look back when advertising first became a medium on TV, there used to be such things as subliminal shots which were banned," said Ms Oakes-Odger. "It was banned because it was considered to be interrupting the natural psyche of one's thinking. I believe video games and violent computer games have the same effect."

Ms Oakes-Odger, who now works with young people highlighting the danger of knife crime, added: "I think many soaps should tone down some of the storylines because the young mind is very impressionable. It has been proven through studies that throughout our adult years our minds are still capable of being malleable to information.

"We have a responsibility as adults to protect our children and the information that is input into them. If

we can't tone down the information they are receiving we must give them the balance of information. We can't allow them to live in a twilight world of reality and non-reality."

Ms Oakes-Odger claimed youngsters were most vulnerable of falling into gangs and violent activity after moving from primary to secondary school.

"In the first year of secondary school when they have so many things to think about like becoming an adult and going through puberty, children want to appear big and confident.

"This can often be something that fuels the possible carrying of weapons to protect themselves."

Evidence-taking by the commission at Birmingham Town Hall will go towards a Channel 4 series - The Truth About Street Weapons - examining gun and knife crime in Britain. It will be broadcast this summer.

Ms Sawyers called for more discipline in schools and for teachers to understand why some children behave badly, instead of immediately expelling them.

She told the panel - including former West Midlands Chief Constable Lord Geoffrey Dear and which is visiting London, Liverpool, Manchester and Glasgow - of her heartache at losing Daniel. "It's something I would not wish on anyone. I take it a day at a time. It really saddens me now that it is still happening. Whatever the Government are doing it's not enough."

Keith Bristow, Chief Constable of Warwickshire Police and the Association of Chief Police Officers' lead on violent crime, said statistics showed gun crime had decreased but many cases were not being reported to police. "We can only solve the problem if we know about the problem," he said.