The committee is not convinced that the IT 'spine' - the national database that will hold patient care records and underpin the national programme for IT - will be reliable enough to allow GPs to meet targets set in the DES, worth £1.30 per patient.
According to the draft DES, published in December, practices will be expected to adopt systems, such as Choose and Book, electronic prescribing and GP-to-GP record transfer. But access to these systems is reliant on a fully functional spine.
The spine has experienced a number of problems over the past month, including slow response times and time-outs on web pages.
Connecting for Health believes the problems have now been resolved, but GPs remain unconvinced.
GPC IT subcommittee chairman Dr Paul Cundy said: 'Clearly spine performance at the level experienced over Christmas might well threaten the delivery of any IT DES.
'The GPC will need reassurance that GPs would not be denied money for problems beyond their immediate control.'
GPC IT committee member Dr Trefor Roscoe said: 'The Spine went down over Christmas. If it had been being used by everyone and that had happened, it would have been chaos.
'I am still concerned about how robust the system will be. We can't encourage people to start using it until we are convinced it is robust,' he said.
Connecting for Health's joint GP clinical lead Dr Gillian Braunold promised that the terms of the DES would ensure that GPs were protected: 'It will say specifically that if a problem is due to something that is not the GP's fault, such as the spine being down, they will not be penalised.'
Dr Braunold added that she had originally expected the DES to be signed off last week but there were issues that still needed to be resolved.