VITAL initiatives aimed at preventing young people joining gangs face an uncertain future.
Funding for the projects, which target teenagers under threat from violent street culture, is due to run out in the next three years.
Former London mayor Ken Livingstone and the Government pledged millions of pounds following a spate of murders in London, including the killing of 14-year-old Paul Erhahon in Leytonstone.
But the economic downturn and mayor Boris Johnson’s refusal to confirm he will match existing funding has raised concern that projects will be forced to end.
Addressing a meeting of the Community Safety Board, Leora Cruddas, the council's head of education for communities, said: "I don't know if the current mayor is going to continue funding.
I can assure you that I will be looking for ways to get the extra money but it is likely there will be a decline in investment because of the economic crisis.
"Most of the money we secured was at a time of great plenty. I will be wracking my brains to find ways to get money for our projects."
Bengali International, of Francis Road, Leyton, provide a youth centre and trips for teenagers, as well as helping young people off drugs and into work, but the money it receives runs out next year.
Co-ordinator Abul Islam said: "If we didn't get the money then a lot of the young people who use our facilities would be forced out on to the streets."
Worth Unlimited works in the borough’s most deprived areas to improve young people’s self-esteem.
Matt Perry, 32, branch director, said: "I don't think we've seen the worst of it yet.
In 12 to 18 months time we will see the full impact. If we don't get as much funding then young people don't get the service."
He added: "I don't think things will implode because we will continue to work with other organisations and look for other sources of funding."
In 2007 the government and Mr Livingstone pledged a £60 million to fund organisations across London. The Government pledged a further £19 million and Boris Johnson gave an additional £5 million to tackle gang problems.
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