Charities are concerned that older patients may suffer because of the government's push to force practices to open for extended hours.
Last week, GPC chairman Dr Laurence Buckman wrote to charities and clinical groups complaining that prime minister Gordon Brown's obsession with extended hours could damage patient care.
Letters were sent to Help The Aged, Age Concern England and the British Geriatrics Society.
Dr Buckman wrote: 'It seems the government has scant regard for older and chronically ill patients in this country. It is more intent on chasing what it sees as political vote winners.
Gordon Lishman, director general of Age Concern, said: 'As older people make more visits to their GP than other adults, it is vital that the government considers their needs in any review of surgery opening times.
'This should include ensuring that longer hours for doctors does not make it harder for them to see a designated GP, and that they are able to book appointments in advance and arrange a home visit when needed.'
A Help The Aged spokeswoman said extended hours potentially benefited all patients.
'Any policy changes should be evaluated thoroughly to ensure that they do not affect existing patients, or people receiving regular care from their GP. We know that continuity of care is vital and people value this.
'The bottom line is that the government needs to consider how properly to fund extended opening hours if they are expecting GPs to provide more services. They need to be able to have the money to do that as well.'