The government has been warned that it must do more to tackle long-term youth unemployment after a new study suggested it could treble by 2011.

The Centre for Cities predicted that the number of under-25s out of work for more than a year would rise from 130,000 in May 2009 to 350,000 by December 2011.

Young people aged between 16 and 24 currently account for 40 per cent of the unemployed, a proportion which could leave 1.18 million out of work by the end of 2011.

The report found that cities such as Hull, Sunderland, Barnsley, Swindon and Doncaster had been worst affected. Hull has the highest rate of youth unemployment in the country, with 9.85 per cent of under-25s claiming unemployment benefit last month, followed by Sunderland at 9.45 per cent and Barnsley at 9.15 per cent.

The group described the government’s £1bn Future Jobs Fund, aimed at creating 150,000 new jobs during 2009-11 for unemployed young people, as a “sticking plaster” that failed to address the risk of mass unemployment.

Dermot Finch, Director of the Centre for Cities, said: “The Government is right to introduce the Future Jobs Fund at this time. But it will not be big enough to help every long-term unemployed young person.

“So it will need to be targeted very carefully on those young people in cities that have seen a recent rise in unemployment due to the recession.

“Cities need to stop the young and temporarily unemployed of today becoming the long-term workless of tomorrow.”

David Blanchflower, who left the Bank of England's monetary policy committee last month, has called for an emergency programme to prevent mass youth unemployment.

He wants the government to ensure that those at risk of unemployment are kept in education and training, by funding extra university places, providing more apprenticeships and raising the school leaving age to 18.