The country's first fully operational private finance initiative hospital has amassed a backlog of about 3,000 'unreported' x-rays since its official opening in April.

National guidelines from the Royal College of Radiologists say x-rays should be assessed and 'reported on'by a qualified radiologist within 48 hours of being taken. This provides a countercheck, allowing radiologists to identify medical conditions that may have been missed by the referring clinician.

But just five months after its official opening by prime minister Tony Blair, Cumberland Infirmary has witnessed a dramatic increase in unreported x-rays, some dating back to July. Trust managers have promised immediate action, but insist that most films have been 'evaluated' for clinical priority, even if they have not been officially reported.

They also say that all unreported films have been seen by either the referring clinician or the referring clinician and a consultant radiologist.

Dr Paul Dubbins, registrar of the Royal College of Radiologists, praised Carlisle Hospitals trust for taking decisive action to tackle the backlog, but said the reporting delays raised the possibility that diagnoses may be delayed or even missed.

'Radiologists are trained to look at images, and those images sometimes have subtle changes which may presage significant pathology, possibly tumours, which may not be obvious on chest x-rays, 'he said. 'Sometimes, it's only the radiologist who has the expertise to see these things. '

Charles Lomas, Society of Radiographers north west regional officer, said members in Carlisle had expressed grave concern at the backlog.

The trust said its x-ray department had been placed under 'additional pressure' by the merger of four x-ray departments under the PFI scheme.

The departments were previously scattered around a split-site hospital.

The trust has also transferred a radiologist to the North Cumbria breast screening programme, leaving the infirmary operating with a half-time radiologist less than the old hospital. A locum radiologist is due to start work towards the end of the month.

Trust chief executive Brian Waite said: 'The trust is appointing additional clerical officers to organise the films for reading, and additional support for the radiologists to undertake this task as soon as possible. '

Mr Waite added: 'An action plan is currently underway and the trust is working towards meeting royal college guidance, but we will require additional resources to achieve this aim. '

He said the action already taken should have 'ameliorated'any potential risks.