GP consortia stand to inherit PCT debts incurred after April, sparking fears that mergers after that date could leave them facing big redundancy payouts.
Jon Restell, chief executive of health managers' union Management in Partnership, estimates just 50 clusters will remain by the end of 2011, based on data from PCTs that have already merged. He believes the rapid contraction will leave too few finance directors by 2012 to help GP consortia manage risk.
He also warned that the NHS Commissioning Board could become 'a sponge' for functions other NHS bodies cannot manage. The Board could become larger than the SHAs it replaces, said Mr Restell.
GPC chairman Dr Laurence Buckman has also warned that PCTs are 'prematurely collapsing', putting extra pressure on consortia to develop quickly.
The DoH estimates it will cost PCTs £541 million in redundancy pay-outs to cut staff by 30 per cent by 2013.
New consortia could be saddled with debt as PCTs cut staff in a bid to cut management costs by 45 per cent.
If PCTs transfer staff to consortia, which then find they are surplus to requirements, GPs face paying out redundancy settlements built up over up to 20 years, experts warn.
Mr Restell said he and the DoH were looking into whether displaced PCT chief executives were 'suitable' for top consortia posts. A recent GP investigation found the number of consortia that have formed is similar to the original number of PCTs - around 300. Health secretary Andrew Lansley has predicted 220 to 240 consortia by 2013.