GPC deputy chairman Dr Richard Vautrey said that fewer GPs would be prepared to work out of hours when extended hours are imposed on practices.
It could result in doctors commuting from Europe to work lucrative out-of-hours shifts. Dr Piotr Robinski made headlines last week when it was revealed he travels for 12 hours from Poland before starting his shift.
Dr Vautrey said there was a limit to how much a GP can work and if they were working later in the evenings, it could potentially lead to fewer working out-of-hours.
A spokesman for Cherry Tree Medical Ltd, the agency that hired Dr Robinski, said that if UK GPs were unable to do out-of-hours due to additional in-hours surgery commitments then the only alternatives were either to have fewer doctors, train more GPs or bring them in from overseas.
The GPC is to poll GPs about whether they accept DoH GMS reforms including opening for an additional 30 minutes per 1,000 patients per week.
Dr Vautrey said the government would not hand back responsibility for out-of-hours because it had been a good way of opening up the market to private companies.