Gang crime is on the rise after what some experts, including the children's minister, call 'disproptionate cuts' to youth services

UK cities should brace themselves for a summer of gang and knife violence as the impact of cuts to youth services takes hold, experts are warning.

Youth violence is already increasing in London. Figures given to the Guardian reveal that serious youth violence increased by 4% year on year across the capital, with a 9.6% hike in knife crime.

There are fears that deep reductions in youth service budgets, particularly to programmes that divert inner-city youths away from gangs and knife crime, could have a devastating impact on crime levels.

Professor John Pitts, who advises several London local authorities on gangs and violent crime, warned that inner cities were likely to experience increased crime as the holidays begin.

"If you cut summer activities for young people as night follows day you will see an increase in crime," he said. "My anxiety is that those gang members who were in school will now be on the streets. Coupled with cuts to the services they use and fewer youth workers who can mediate, those streets will be a lot more dangerous and I would expect the level of crime and violence to rise."

Gang violence, including peer violence against girls and young women, is increasing, he said. "It is getting worse, it is becoming more embedded and more serious – this is not the time to be pulling the plug."

Eight teenagers have died in London already this year, including Negus McLean, 15, who was chased by seven youths on bicycles before being stabbed. Earlier this month Yemurai Kanyangarara, 16, died after being stabbed in the neck – two 15-years-old youths and a 14-year-old boy have since been arrested.

According to Scotland Yard the number of recorded knife-crime injuries in London went up from 941 to 1,070 in the three months between February and April this year compared with the previous three months; victims in the 13-24 age group injured during knife crime increased by more than 30% between 2008-09 and 2010-11.

Youth services, particularly those that prevent gang violence, have been savaged by local authorities because of government-imposed cuts. More than £100m was removed from local authority services for young people up to March this year, according to the Confederation of Heads of Young People's Services, which surveyed 41 of their members. Budget cuts imposed at the start of the financial year averaged 28%, but some local authorities were cutting 70%, 80% or even 100% of youth services, it said. Almost 3,000 full-time staff who work with youths have been lost.

Universal services such as youth clubs have been hit hardest: 96% of the 41 heads of youth services who responded said club activities would be either reduced or stopped altogether by April next year.

MPs on the education select committee warned parliament last month that "disproportionate budget reductions" could have "dramatic and long-lasting" consequences. Graham Stuart, the select committee's chairman, said the current situation was "damaging" and an increase in crime was "inevitable". He said: "Tim Loughton [the children's minister] has said that cuts to children's services are disproportionate and we agree."

Youth services have been cut in every area of the country. According to the union Unison, Norfolk, Suffolk, Buckinghamshire and Manchester part of a "growing number of local authorities planning to get rid of the youth service altogether". Birmingham is likely to reduce youth services by 50% over the next three years; Haringey and Hull local authorities have cut 75% of its their youth services; Warwickshire is facing an 80% cut; the prime minister's Witney constituency, in Oxfordshire, has closed 20 out of 27 youth centres – there is not a youth service in the country that remains untouched.

At the same time London Councils – a lobbying organisation that promotes the interests of the 32 London boroughs, the City of London, the Metropolitan Police Authority and the London Fire and Emergency Planning Authority – has warned about the consequences of slashing funding to youth-offending teams by as much as 30% in some boroughs.

And the Youth Justice Board is to be scrapped, leading MPs to warn that the move could prove costly if crime rates rise.

The government hopes the voluntary sector will play a bigger role in tackling the youth violence, announcing £18m of funding earlier this year to help charities tackle knife, gun and gang crime after Brooke Kinsella, the actress turned knife crime campaigner whose brother Ben was killed in 2008, released a report.

Some charities argue this is not new money, and with 70% of voluntary organisation funding coming from already squeezed local authorities, according to the union Unison, some in the sector fear charities will be unable to provide a comprehensive system.

Smaller charities, while doing positive work, can be unco-ordinated and much effective inter-agency work will be lost, warned Mick Hurley, an adviser to Greater Manchester police on serious youth violence, who was awarded an OBE last year for services to young people.