The NHS is at risk of a "brain drain" and hundreds of surgeries face closure if older family doctors are not retained, the Royal College of GPs (RCGP) has warned.
The doctors' membership body said some 594 practices across the UK, including 467 in England, are at risk of closing because three quarters or more of their GPs are aged 55 or over.
RCGP chairwoman Professor Maureen Baker has written to Health Secretary Jeremy Hunt to urge him to make retaining the older workforce just as much of a priority as recruitment.
She also warned that a pledge to boost GP numbers to 5,000 by 2020 in NHS England's General Practice Forward View could not be achieved through recruitment drives alone.
Her calls echo those of other GP leaders who have said excessive workloads are affecting doctors, who are increasingly turning to part-time work.
Prof Baker said:
Prof Baker outlined a five-point plan in her letter, which includes a scheme of flexible working for older doctors, a bursary scheme to help GPs meet the costs of indemnity and a review of pension arrangements to ensure they are not a disincentive.