Ministers have defended changes to school sports funding after 75 top British athletes warned they could risk the "future health of children"
Olympic champions Denise Lewis, Tessa Sanderson and Jason Queally said the end of direct funding for school sports partnerships was "ill-conceived".
Labour have accused ministers of an "act of vandalism" and urged a rethink.
But Education Secretary Michael Gove said the current system was too bureaucratic and of "variable quality".
Ministers were looking at the funding available for schools sports, Mr Gove told MPs during a debate called by Labour on the issue.
While offering to work with the opposition to ensure an "ever higher standard" of provision, he said they must accept the real budgetary pressures and the need to provide "maximum" value for money.
The issue has risen up the political agenda after David Cameron and Ed Miliband clashed over the subject in Parliament last week and each side has accused the other of selective use of statistics about pupil participation to back up their arguments.
Labour says ending annual ringfenced funding for the partnerships, set up in 2006 to encourage sport and PE in schools, will undermine the progress in boosting participation in recent years.
In a letter to David Cameron, organised by Olympic badminton silver medallist Gail Emms, the elite athletes warned that the move could have serious long-term implications in the fight against child obesity and illness.
"With one ill-conceived cut you are on the brink of destroying everything schools, clubs and the national governing bodies of sport are doing to ensure this and future generations embrace sport and physical activity," they wrote.
"We cannot stand by and watch as your government threatens to destroy any hopes this country has of delivering a genuine London 2012 Olympic and Paralympic legacy."
The letter urges the government to reconsider the withdrawal of direct funding in March for the 450 partnerships - alliances of sports colleges, primary, secondary and special schools in England to increase sporting opportunities for young people.
"The future health of all our children is at risk if you axe this funding," they added.
Opening Tuesday's debate, Shadow Education Secretary Andy Burnham said the athletes' letter - written in "pretty strong terms" - added to the "chorus of disapproval" over the plans.
Accusing ministers of a "senseless act of vandalism" over the changes, he said: "It is the right of every child to have good sport while at school. It cannot be left to random chance and the occasional goodwill of teachers."
Mr Burnham said he would accept a reduction in funding for schools sports partnerships as long as the "basic infrastructure" - including a sufficient number of co-ordinators - was kept in place.
Mr Gove said the £2.4bn invested in school sports over the last seven years had yielded improvements but there had been no increase in participation in sports such as swimming, rugby or hockey.
"While much good work was done, the money was not spent as efficiently and effectively as it should have been," he told MPs. "The picture is not perfect. Far from it."
One in three pupils did not take part in internal school competition, he said, while more than 700 schools did not offer pupils the opportunity to compete against other schools.
No 10 has insisted the partnerships are not being dismantled and it is looking at ways of setting them up on an independent footing so schools may be able to buy "sports services" from them.
As part of its efforts to encourage competition between schools, the government is setting aside £10m to establish an annual "Schools Olympics".
Ministers have said they expect schools to continue offering pupils a minimum of two hours of sport or PE a week, pointing out that the schools budget will rise by £3.6bn in cash terms by 2015.
But sports charities have warned that if schools are asked to fund the programme themselves out of existing budgets, many will prioritise academic subjects or basic PE provision rather than sport.