The Government said this week that plans to let all teenagers attend summer camps would improve schools' results and racial integration, though its own research suggests otherwise.
Department for Education and Skills' research on a summer schools pilot project last year revealed "negligible" mixing of young people from different backgrounds because few participants came from ethnic minorities.
It says the vast majority of the 1,640 young teenagers who took part in the camps enjoyed them, with nearly all saying they would recommend them to a friend.
Only 16 per cent said the programme had given them greater confidence, however, and more than half of the older participants said the camps had not improved their performance in the activities they had tried.
"The programme's effect on longer-term outcomes such as learning and life skills, and the facilitating effects of social mixing remain to be seen," the report said.
The findings were published as the Government unveiled the latest stages of a plan to provide every secondary pupil in England with the chance to spend at least seven days during his or her holidays at residential summer camps.
More than 2,500 young people will take part in its Get REAL (Residential Exciting Active Leisure Time) programme this summer and places will be available for more than 20,000 from next year.
Parents are being asked to pay pound;25 for the breaks if their child is eligible for free school meals and up to pound;100 if they are higher earners.
The camps are being subsidised by the National Lottery, which will spend pound;12.5 million on the scheme over three years.
Activities which teenagers will be offered range from abseiling and kayaking to Fame Academy-style singing contests and basic robotics.
David Miliband, the school standards minister, said that the summer camps would improve pupils' participation and achievements in education.
He said the English scheme was a "third way" between the private camps run in America and the state-funded camps in France.
"I can see significant educational benefits from mass access to summer camps," he said. "We know that the holiday is a fallow educational period.
We know there is a dip in achievement - particularly in the primary to secondary transition.
"It is very important that these young people get to meet each other across barriers of income, class, race and religion and this programme helps put that into practice."
Trevor Phillips, chairman of the Commission for Racial Equality, also called this week for the creation of summer camps so children could make friends with people from other races.