The goodwill of private schools with top-of-the-range sports facilities will not be enough to fill the gap after the Government scraps its national school sports scheme, a leading prep school head has warned.

Andy Falconer, chair of the Independent Association of Prep Schools, said plans to shelve the 450 school sport partnerships would be “a devastating loss for a generation of children”, and that although independent schools often loaned facilities to state schools, the Government “could not rely” on them to pick up the slack.

Mr Falconer added that the loss of a network of 225 “competition managers”, who arranged events between state schools, would put the burden of organisation back on to hard-pressed teachers.

His comments come as 3,000 young ambassadors for the School Sport Partnerships prepare to descend on London next month, to protest against plans to divert the scheme’s pound;162 million annual fund into the general education budget - leaving it to the discretion of heads where the money will be spent.

Critics of the decision fear the work of the programme, which has been running for four years, will be destroyed, resulting in a return to a lottery of sports provision in maintained schools.

The Youth Sport Trust, which helps run the programme, claims that more than three million young people were involved in inter-school competitions in 200910, up from 1.6 million in 2006 when the partnerships were first introduced.

The ambassadors have launched a campaign to gather a one-million signature petition and a Facebook group has gathered more than 14,000 supporters.

Mr Falconer, head of St Olave’s School, a prep school in York, is a keen sportsman, but has bitter memories of his state-sector education in Scotland, when he had to play rugby at a local club because teachers were “working to rule”.

He said St Olave’s organised an annual football tournament for 10 local state primaries, but added that small gestures from individual private schools were not the answer to a nationwide problem.

“Organising competitive sport between schools will fall back on enthusiastic teachers, who will have to jump through so many health and safety and admin hoops before they even get in the minibus.”

Education secretary Michael Gove insists that partnerships are not being scrapped, it will just be up to headteachers how they support them.

Sporting chance: `Big difference’ in primary pupils

John Simon, head of PE at St Aloysius’ College, a comprehensive in north London, believes the School Sport Partnerships will be badly missed.

“Since they were introduced, we’ve noticed a big difference in the standard of primary pupils coming up,” he said. “They try more activities and they’re more ready to start on sports.

“We’ve really benefited from the competition managers. If the managers go, it will be left to teachers to do it voluntarily, but they know they won’t be paid.”

He said the school’s annual trip to play football at the private Lancing College near Brighton was a great experience, but “did not provide the answer” to improving school sport generally.

• Original headline: Don’t assume we’ll pick up slack in sport, independents warn