Image caption The police control room at Bilston Glen was out of action for several hours

A police control room recently criticised in a watchdog report was unable to take 999 calls for several hours on Tuesday morning.

A "technical difficulty" at Bilston Glen in the early hours of the morning meant 999 and 101 calls had to be diverted to other centres.

The control room took the initial call after the fatal M9 crash, which police failed to investigate for three days.

Police Scotland confirmed the fault at the centre had now been resolved.

A tweet from Unison, the union which represents many police staff in Scotland, said the call centre had been taken out of action at 03:30 on Tuesday, but Police Scotland said the public would not have noticed any difference in the level of service.

Ch Supt Alan Speirs said: "I can confirm that in the early hours of Tuesday 15 December 2015 the Service Centre at Bilston Glen experienced a technical difficulty which resulted in 999 and 101 calls being diverted to other regional service centres. The issue has now been resolved and the system is working normally.

"Police Scotland has robust and tested plans in place for eventualities such as this and I am pleased that they worked extremely well.

"There was no interruption to the emergency and non emergency services and no delays in calls being answered or officers being dispatched."

'Poor call-handling'

Staffing shortages at Bilston Glen were highlighted after an HM Inspector of Constabulary (HMIC) report into the M9 crash in July in which Lamara Bell and John Yuill died.

Ms Bell, who was discovered critically injured in the crashed car, had been in the vehicle next to her dead partner Mr Yuill for three days. She died later in hospital.

Police Scotland admitted they did not investigate a report they had received about the crash until three days after it happened.

In the report, HMIC Derek Penman said Bilston Glen had insufficient staff and that this had resulted in poor call-handling performance, although he noted the force had made "considerable efforts to address this".

The Scottish government said in September it would delay plans to two close police call centres in Aberdeen and Inverness in line with the recommendations made by HMIC.

Scottish Liberal Democrat leader Willie Rennie said he had become aware of the problem when a member of the public told him their 101 call had not been answered.

He said the public should be given more information about how to communicate with the police when the system is down.

Scottish Labour's justice spokesman Graeme Pearson said the shut down of Bilston Glen "suggests a failure to learn the lessons of the HMICS report into call handling, which exposed systemic, fundamental failings because of the SNP government's botched reforms of our police service."

Margaret Mitchell of the Scottish Conservatives said it was particularly concerning that Bilston Glen had been out of action at one of its busiest times of the year.

"This would be hugely concerning at any time but especially in the run up to Christmas and New Year, one of the busiest times of the year.

She added: "Furthermore the fact it happened at Bilston Glen control room, which was the control room involved in the tragic M9 crash case, makes complete nonsense of the cabinet secretary for justice's standard response that 'it's all sorted now'."