National guidance for PCTs suggests merging practices that are no longer financially viable because of changes to the prevalence formula in 2009/10.
Practices that lose out could also be switched to APMS contracts, the advice says.
Guidance developed by Primary Care Contracting (PCC), an NHS body that promotes best practice in commissioning and contracting, says PCTs should not promise financial support to practices facing losses.
The document makes clear that it is 'mandatory' for PCTs to open discussions with LMCs or practices that lose out.
But it cites 'risks of adverse publicity from losing practices and LMCs', and the opportunity to 'put a positive spin on this' as key motivating factors.
Prevalence losses, which will run to six figures for some practices, could force tens, possibly hundreds, of practices to close if alternative funding arrangements are not agreed next month, according to the GPC.
But the PCC guidance advises PCTs not to set a precedent by funding local enhanced services (LESs) for struggling practices.
'Do not suggest to LMCs that the PCT will offer LESs to compensate,' it says.
'You could point to the benefits to be derived from possible practice mergers,' it adds.
Switching practices to APMS deals 'might secure their income but allow the PCT more opportunities to improve performance/quality/access, i.e. a win-win', the guidance adds.
West Midlands GP and GPC member Dr Fay Wilson said that a small number of PCTs would like to destabilise practices to watch the market develop in general practice.
'They tend to play with it like a train set, not like they are trying to secure the best care for patients,' she said.
After concerns that many PCTs were not talking to practices that stood to lose out, the GPC said last week more were beginning to do so 'because of all sorts of pressure'.
GPC chairman, Dr Laurence Buckman, said: 'At least this guidance is encouraging PCTs to engage with LMCs and affected practices, which is a start.'
The PCC document also shows that many PCTs have still not used the DoH's simple online calculator which estimates how much their practices will lose under the 2009/10 contract.
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