The monthly rise in cases this year is up 30% on 2008.

The rise may signal that trusts are clamping down on poorly performing doctors in advance of revalidation.

‘The referrals are coming mainly from the NHS and they are not trivial,' said GMC chairman Professor Peter Rubin.

‘It's likely to be a precursor to the introduction of revalidation. Employers are beginning to take stock,' he explained.

The increase is so great that doctors up before the GMC are waiting longer for investigations and hearings.

The GMC admits that it has missed its own targets of nine months for hearings to be concluded and six months for investigations to be completed.

In July almost one third of cases missed the GMC's self-imposed target of nine months from referral to adjudication hearing.

In 11 cases, doctors waited longer than nine months for their adjudication hearing to start.

In the same month, 50 out of 391 doctors saw their investigation drag on beyond six months.

The council said it expected to be back on track by the end of the year.

• Why do you think the number of doctors reported to the GMC is increasing so much?
• Read the full version of this story in this week's edition of GP dated 25 September.