The investigation into whether Michael Matheson misused his expenses to help cover an £11,000 iPad bill will proceed “quickly”, Holyrood bosses have said. 

However the cross-party body in charge is not expected to question the SNP health secretary in person, and will instead rely on written evidence.

The probe is expected to take weeks rather than months, although the approaching festive break means it might not report until next year.

The Scottish Parliamentary Corporate Body (SPCB) announced last week that it intended to hold an investigation into the Matheson affair, which has now rumbled on for three weeks.

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Mr Matheson admitted earlier this month that his teenage sons had run up the data roaming charges bill watching football on a family holiday in Morocco last New Year. 

The boys had used his Holyrood-issued device as a hotspot, and because the Falkirk West MSP had failed to replace an out-dated SIM card, the costs were astronomical.

Mr Matheson charged £3,000 of the £11,000 to his parliamentary office expenses despite not knowing the reason behind the bill, effectively leaving taxpayers to pay for the lot.

Four days after he learned from his wife on November 9 that his sons were to blame, he told the media there had been no personal use and blamed the old SIM card.

He has agreed to repay the £11,000 in full.

Opposition parties have accused him of lying and demanding he reign - and accused Humza Yousaf of poor political judgment in not sacking him.

The SPCB will now investigate Mr Matheson’s expenses claim, and could refer the matter to Holyrood’s Standards Committee for further work.

The Committee could in turn ask the Ethical Standards Commissioner to investigate.

Tory MSP Craig Hoy demanded a full timetable to be set out.

In a letter to Presiding Officer Alison, who also chairs the SPCB, he wrote: “The significant amount of interest generated from this scandal means it is imperative for the SPCB to provide details about this investigation so that the public can be confident that a thorough investigation has occurred and that it won’t be a whitewash.

He asked when the investigation was due to be completed, when findings would be published, if Mr Matheson would be given advanced sight of the report, and whether correspondence between Holyrood officials and the Health Secretary would be published.

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He also pushed the Presiding Officer, who is on leave following planned surgery, on whether there would be a full parliamentary debate on the findings.

He said: “If these outstanding queries are addressed, that would give the public the reassurance they need that this investigation will be comprehensive and will answer why Michael Matheson felt it was appropriate to claim nearly £11,000 from the taxpayer to pay for the bill he incurred whilst on holiday.”

A Scottish Parliament spokesperson said: “The SPCB’s investigation will proceed quickly and with due regard to the need for a fair process and the requirements of the Code of Conduct set by Parliament.

“Due process requires that Mr Matheson will be invited to contribute evidence in writing following the personal statement that he made to Parliament on 16 November.

“The SPCB has already made clear that in the interest of fairness to all, and to avoid prejudicing the investigation, it will not comment on any further matters that could have a bearing on the process or provide a running commentary.

“The Corporate Body remains wholly committed to openness and transparency and will release all material it can, when it can, in line with its legal obligations.”