In three PCTs, combined emergency and elective admissions rose by more than 20 per cent, a report by independent health analysts CHKS shows.
Admissions in Coventry PCT were the fastest rising in England. They topped 20 per cent in Mid Essex and Milton Keynes.
Dr Richard Vautrey, GPC deputy chairman, said: 'This will undoubtedly lead to more monitoring of GP referrals. But it is largely systems, targets, and hospital funding arrangements outside the control of general practice that need to be tackled.'
The rise, reported in Are Hospital Admissions Out Of Control?, undermines claims that care is shifting from the acute sector into primary care.
CHKS found that hospital admissions had risen in England, Wales and Northern Ireland in the year to March 2009.
They were up by 5.4 per cent in Wales and 3.7 per cent in Northern Ireland.
A huge increase of over 9 per cent in elective admissions in Wales is likely to be due to a bid to cut waiting times, CHKS said. Patients were admitted from out-of-hours services, NHS Direct, and A&E as well as from GPs.
Dr Paul Robinson, head of market intelligence at CHKS, said: 'With PCTs facing a funding squeeze ...
they will inevitably be looking at GP referrals into hospital.'
Dr Vautrey blamed high referrals on factors including the four-hour A&E target and hospitals discharging patients and expecting them to be re-referred to another specialist.