ALL chemotherapy patients whose treatment was cancelled following a massive computer ­failure at Scotland's largest health board will be treated by next Wednesday.

NHS Greater Glasgow and Clyde, who had to delay appointments and treatment for more than 700 patients this week after the technology meltdown, said some of those affected have already been given new dates.

The 48 people who had to go without scheduled chemotherapy have been promised the treatment they need during the next five working days.

Robert Calderwood, chief ­executive of NHS GGC, has also confirmed the computer systems are now back up and running.

Technicians had been working to restore the clinical and administrative programmes used by the health board since Tuesday, when the fault was discovered.

Staff from the two software companies involved, Microsoft and Charteris, worked with employees from the health board and the Scottish Government to get to the bottom of the problem.

The issues began when a key program on the health board's computer system became corrupted over the weekend.

"This was a corruption of a ­software program which, therefore, moved from server to server," Mr Calderwood said.

"In the past 48 hours we have had interactions with 10,700 patients and we have only had to cancel, as of last night, 709 patients. We unreservedly apologise, and I personally apologise to those 709 patients.

"But almost 10,000 patients' treatments went ahead as normal over the past 48 hours."

Mr Calderwood said 99% of all IT networks across the UK are built on the relevant program called Microsoft active directory and it was the first time the health board had experienced a fault in more than 10 years working with Microsoft.

Mr Calderwood added: "Microsoft itself says it has never had such a fault reported across many years in all of its business areas.

"To that extent, the issue for us is now to identify how the software program became corrupted and make sure if there are lessons to be learned we do take these on board and increase our resilience and our back-up."

Yesterday Health Secretary Alex Neil announced to MSPs at Holyrood he had instructed a robust review right across the National Health Service in Scotland.

All health boards are to be instructed to make sure their systems are robust and that their back-up systems are robust.

In a statement, NHS GGC said it was very keen to see all patients affected given new appointments and added it may run extra clinical sessions to ensure people are seen swiftly.

Tory health spokesman Jackson Carlaw said the problem was "not a failure of policy or management but a failure of a system".

The Conservative MSP praised the "work that has been done in order to resolve it as speedily as it has been".

Mr Neil stressed ­emergency and maternity services at hospitals in the health board's area had been maintained throughout.

He also insisted every effort would be made to ensure those patients who had been affected received new appointments as quickly as possible.

Mr Neil said this could mean some NHS staff having to work longer hours "perhaps for a short period of time" to help ensure all patients who have had appointments or treatment delayed are seen "in a reasonable period of time"