Some areas of the country did not have enough space to house offenders

The Commons public accounts committee said the sentences must be "effectively and consistently" administered to be a "credible" alternative to custody.

The MPs questioned the amount being spent on custody for youngsters.

The Youth Justice Board, which helps to rehabilitate youths in England and Wales, is to examine their findings.

In the field of community sentencing, the report found the flagship Intensive Surveillance and Supervision Programme (ISSP) was completed by fewer than half of those sent on it.

The ISSP involves curfews and 25 hours a week of therapy and education for offenders.

The report said: "The board should identify why some offenders fail to complete the programme and review differences in the way Youth Offending Teams manage offenders on the programme."

The Youth Justice Board needs to work closely with the courts to ensure there is sufficient space in custody on the one hand, and to improve the courts' confidence in community service on the other Edward Leigh Drive to improve youths' image

The MPs' report finds rates of jail terms for young offenders differed widely across England and Wales.

Providing jail places for young offenders used �283m of the board's �394m annual budget.

But the report found that, of the 7% of young offenders given custodial sentences, 80% reoffended on their release.

Committee chairman Edward Leigh said the levels of re-offending showed "locking up these offenders is only part of the answer".

He said: "The Youth Justice Board needs to work closely with the courts to ensure there is sufficient space in custody on the one hand and to improve the courts' confidence in community service on the other."

The committee found the board had difficulty finding space for young offenders in some areas of the country, particularly in the south east and south west of England.

It meant some offenders had to be housed in other areas, sometimes far from their families, which harmed the offenders' chances of rehabilitating properly.