The Nursing and Midwifery Council is struggling to deliver its pledge to deal with the vast majority of fitness to practise investigations within 15 months of referral.
As the regulator gears up for an external audit, latest figures have revealed its attempt to clear 3,525 active cases is being hampered by a continued backlog of work.
The NMC had promised that 75 per cent of cases would be managed with 15 months in the first quarter of the 2010-11 and 90 per cent by the year end. It also recruited extra staff to speed up the process, following strong criticism for delays.
But performance has plateaued over the last two months, with around 66 per cent of cases resolved within accepted time limits.
A spokeswoman for the NMC said, while it has set itself ambitious targets, the regulator does not want the quality of the work to suffer.
She said: “ We still have a number of old cases which we have been investigating for some time and we are focussing our efforts on clearing these and are providing additional resources to do so.
“Until we have been able to do that and improve timelines in new cases we do not expect our performance against this key performance indicator to improve as much as we would like. “
The Council for Healthcare Regulatory Excellence next week starts its annual audit of NMC casework.
Chairman Harry Cayton said: “We will be looking at what actions the NMC has taken to implement its improvement plans for the fitness to practice process.”
Since December 2008, the number of cases facing a long wait for a hearing has fallen from 192 waiting over nine months to 132 waiting over six months.