Doctors have claimed their surgery will close if "catastrophic" changes to GP funding go ahead.

At a public meeting this week GPs and staff from Vineyard Hill surgery in Wimbledon Park told hundreds of worried patients a new funding regime set to arrive this April could see the practice shut its doors within 18 months.

Practice manager Beverley Snell urged patients to contact Sutton and Merton Primary Care Trust (PCT), which is implementing the new system, and demand it scraps its plans - which she claimed would cost the surgery £200,000, or 43 per cent of its income. She said: "The impact for our practice is catastrophic."

It is thought the changes could see more cash diverted to other surgeries in the borough - but Ms Snell said Vineyard Hill stood to lose 13 per cent of its income in April and a further 13 per cent 12 months later. Dr Jill Provost, one of two GPs at the practice, said: "These losses are unsustainable...it's difficult to see how the practice could survive."

Wimbledon MP Stephen Hammond told Monday night's meeting was likely to have a negative impact for other GPs in Wimbledon, and criticised . He said: "This is about a local bureaucracy and a local bureaucrat gone mad."

Staff at the surgery, which has about 5,500 patients on its books, said the changes would mean it was only feasible to run 70 of the almost 300 appointments a week that currently take place.

The PCT is changing the formula used to calculate the per patient funding for every surgery in the two boroughs. But staff at the surgery said they had not seen the detailed calculations used to reach the new amounts.

During the meeting at the Christ the King Church in Crescent Road, Wimbledon Park on Monday angry patients suggested mounting a legal challenge to the move - something the practice is considering - as well as a public campaign against it.

A spokesperson for NHS South West London, which oversees the trust, said: “NHS South West London is responsible for commissioning high quality care for all patients across South West London; reducing variation in service provision and addressing health inequalities.

“We are currently reviewing primary medical contracts with all practices in Sutton and Merton in order to provide equal access to primary care and we will ensure that no practice is disadvantaged during this process.”