GMC chief executive Niall Dickson said an extension was 'unlikely'.
A recent GMC survey found concerns among trainers at the competence of trainees (GP, 15 October). But Mr Dickson added that he did not have the evidence to conclude that longer GP training would solve this problem.
The RCGP has led calls to lengthen GP training. The college's White Paper response said 'extending training to five years will ensure GPs' clinical decision making, understanding of secondary care, ability to commission and manage resources and facilitate patient choice will be greatly enhanced'.
RCGP chairman Professor Steve Field warned at its conference this month that trainees were not offered the breadth of training previous generations benefited from.
He said time constraints mean GP trainees do not get enough exposure to long-term conditions, and that the quality of out-of-hours training has fallen.
'In the future, training should be longer,' Professor Field said. 'Everyone should have to do placements in paediatrics and have the flexibility to focus on particular areas of interest.'
Dr John Spicer, director of GP education and head of the London Deanery's GP School, agreed that longer training may be needed for GPs to become 'fully proficient' at all areas of the MRCGP curriculum.
But he warned that this should be in conjunction with other changes to training.
'Simply lengthening the duration of training on its own is not enough to guarantee improvement,' he said.