The British Medical Association has said it has anecdotal evidence to suggest many doctors are closing their lists to extra patients.

Doctors say they are overstretched and are unable to cope because of a major shortage of GPs across the UK.

It is something we have been warning the government and previous governments about for some time

Dr Hamish Meldrum, BMA

Under existing rules, doctors can refuse to add patients to their list if they feel they are looking after too many already.

However, a primary care trust - which coordinates GP services at a local level - can force a doctor to add a patient to their list if there is no space with other doctors in the area.

'Serious problem'

Dr Hamish Meldrum of the BMA's GPs committee said: "It is quite a serious problem and it is something we have been warning the government and previous governments about for some time."

Dr Meldrum said it was difficult to determine the extent of the problem. There are no official figures for the number of doctors who have closed their lists.

But Dr Meldrum said it was "certainly into the high hundreds of practices which is thousands of doctors whose lists are closed or who are reluctant to take on new patients."

Many of the problems occur when a GP retires and a practice is unable to recruit another doctor.

"They are left with a higher list of patients to look after and find the only thing they can do is to take no new patients," Dr Meldrum said.

He added that his own three-doctor practice in East Yorkshire was forced temporarily to close its lists when it was down by two full-time GPs and there was a delay in recruiting replacements.

New contract

Dr Meldrum said the problems could be solved in the long-term by a new contract and better working arrangements for GPs.

There is a full blown crisis in general practice

Dr Liam Fox, Shadow Health Secretary

The BMA is currently in detailed negotiations with NHS managers over a new contract.

But Dr Meldrum said increasing GP pay, persuading existing doctors not to retire and allowing others to come back to work part-time could also help.

He criticised efforts to recruit GPs from overseas saying it was like putting "a sticking plaster on a gaping sore".

Health Minister Hazel Blears said the government was committed to recruiting thousands of more GPs.

"The people are in the system and are coming through," she told the BBC.

"The whole system has been underfunded for decades and GPs as much as anyone else in the health service need to increase."

Shadow Health Secretary Liam Fox said: "There is a full blown crisis in general practice."

He added: "These problems will be exacerbated by the large number of GPs due to retire shortly. The government seems to have no clue at all about the true seriousness of the crisis it has created."

Liberal Democrat health spokesman Dr Evan Harris said: "Closed lists would hit the poorest in society hardest, particularly in inner cities.

"A situation could easily develop where people simply went to casualty because they could not see a GP. The crisis in primary care must not be allowed to become a crisis in accident and emergency departments."