High exception reporters could be gaining more than £15,000 a year through their exception reporting - approximately 12 per cent of their total funds from the quality and outcomes framework.

The figure comes from yet-to-be-published research by the National Primary Care Research and Development Centre.

Exception reporting can increase GP practice income by making it easier to meet individual targets in the quality and outcomes framework because excluded patients are not counted.

The centre's clinical research fellow Dr Tim Doran said practices in England would have been paid approximately£17m less in total last year had they not been able to exception report.

Most average-sized practices gained between just£1,050 and£2,700 through exception reporting and had an overall exception rate across all indicators of around 5 per cent.

But Dr Doran said some practices gained over£15,000.

"That's not to say all of that is inappropriate - the practice may have legitimately excluded those patients," he said.

There is no evidence that the GPs named by HSJ as having the highest exception rates have been gaming the system.

Of the 15 practices two are now under new management and another said the rates related to a period when the practice was dependent on locum staff.

Three practices said that the main reason was patients not responding to invitations to attend the surgery.

Three others said their high rates were due to the make-up of their patient populations - either very elderly and in care homes or patients with special needs.

One said it had experienced a problem with its software and six declined to comment.