An “unprecedented IT issue” has forced NHS Greater Glasgow and Clyde to postpone more than 500 patient appointments over the past 36 hours.

The issue relates to the health board’s network, which means staff are struggling to connect to clinical and administrative systems.

The health board’s chief executive, Robert Calderwood, said in a statement at lunch time today that the problem, which occurred yesterday morning, is not yet resolved.

This has meant that over the past 36 hours 564 patients have had their treatment or appointment postponed.

“The unprecedented IT issue relates to our network and the way staff can connect to some of our clinical and administrative systems,” he said.

“Our senior management team, IT specialists and clinical leads have been working around the clock and will continue to do so until this issue is resolved.”

Greater Glasgow and Clyde, which uses the TrakCare patient administration system from InterSystems, began experiencing network issues on Tuesday morning and has been working to fix it since.

In today’s update, the health board says it is still experiencing issues, but has re-established a basic level of IT to “enable some of the clinical services affected to resume normally.”

“Further work will be carried out during the afternoon to ensure that this recovery is sustainable and that full IT functionality is restored.”

Over the past two days, the board has cancelled more than 450 outpatient appointments and around 50 chemotherapy treatements.

“Those which have had to be postponed were as a result of clinical decisions taken because the treatment or consultation was reliant on detailed imaging and other patient information which was unavailable as a result of the network issue,” said Calderwood.

“Arrangements have also been made to maintain the vast majority of chemotherapy sessions today although a small number of sessions have regrettably been postponed.”

Greater Glasgow and Clyde has also experienced delays in calls to the switch board.

The health board covers 12 major hospital sites and 80 systems, which are linked through a clinical portal.

BBC reports that the problems may have affected up to ten of the health board’s hospitals.

EHI understands the problem is with the domain system translation from the URL to the IP address meaning staff cannot connect to machines and use applications.

The board is working with Microsoft on a fix for the problem.