London's parks could become inaccessible to the public as a lack of funding makes it increasingly likely they will be sold to private companies, a committee chair has warned.
Councillor Julian Bell said "horrendous" cuts put the parks at risk if councils are forced to sell them.
His comments come as the organisation warns boroughs' spending on parks has fallen by 18% in the past four years.
The government said councils should work with communities to ensure access.
Although the royal parks would be protected from any privatisation, the capital is around 40% green space, according to the City of London.
London Councils, which represents 32 boroughs and the City of London, said budget cuts had put local services, such as social care, under pressure.
It warned funding for community groups and volunteers who maintain the parks is under threat, as they prioritise other services, such as looking after homeless people.
If the cuts continue, councils may be unable to stop the parks being sold off and run privately by 2025, it warned.
Councillor Julian Bell, chair of London Councils' Transport and Environment Committee, said: "We have got to do everything we can to protect our parks for our future generation."
He speculated that one scenario could see health clubs buy the spaces up as they are considered "fantastic assets", in which case the public could have no access, as they could be reserved solely for members.
A Department for Communities and Local Government spokesman said: "All councils should work in partnership with local communities to ensure they have access to excellent parks and green spaces."