The Government is in danger of throwing away "the jewel in the NHS's crown" if it forces GPs to extend their hours without extra investment, a Midland doctor warned yesterday.

More than 300 angry medics met behind closed doors at the Clarendon Suites in Edgbaston, Birmingham, on Monday to consider plans to make surgeries open until 8.30pm on a weekday or a Saturday morning.

The meeting took place after Health Secretary Alan Johnson revealed he had written to every GP in England to explain why he wants surgeries to open in the evenings and at weekends.

Mr Johnson decided to communicate directly with GPs as he was "unhappy" about the way the negotiations had been represented by the leadership of the British Medical Association.

But members of Birmingham Local Medical Committee fear implementing the extra hours, without added financial support, could "be detrimental to patient care."

Dr Robert Morley, the body's executive secretary, explained feelings were running high in the city's medical community.

Doctors are now waiting to take part in a national poll, to be conducted by the BMA to officially gauge the profession's views on extending surgery hours.

Practices could face losing, on average, £36,000 in funding if they do not implement the Government's proposals.

Dr Morley, who has practised in Erdington for 20 years, said: "What we object to is trying to force change on us without extra funding, not extra pay but enough money to fund support services if surgery hours are extended, and their promises of extra investment are not true.

"You can't use patients' healthcare as a commodity, as you might see with supermarkets, it's just not possible.

"GPs surgeries are run by doctors for the benefit of patients and the profession is very angry that the Government wants to throw away the jewel in the NHS's crown, the best GP service in the world.

"It's the relationship doctors develop with their patients by investing time and effort into their community, whereas private sector surgeries would be run by locums who couldn't offer the same continuity of care."

The Government wants GP surgeries to open for an extra 30 minutes for every 1,000 patients, in blocks of 90 minutes. For a GP practice with 6,000 patients, this would mean an extra three hours a week.

The BMA is willing to have surgeries open for an extra two hours on average, the equivalent of 6.30pm to 8.30pm on a weekday evening or a Saturday morning surgery.

Dr Morley added: "There is no talk of industrial action, but I do hope the Government get the message loud and clear that GPs in Birmingham, across the Midland and the rest of the country are not happy at all with this level of enforced change and interference."