The Scottish health secretary, Michael Matheson, is being investigated by Holyrood authorities over the near-£11,000 bill racked up on his work iPad. The Scottish parliament announced on Thursday its ruling body had begun an inquiry aimed at protecting the integrity of its expenses scheme and ensuring public confidence in Holyrood had not been damaged by the controversy. The investigation, which could lead to Matheson being referred to Holyrood’s standards committee or having his rights to expenses curtailed, was announced after the health secretary admitted his sons had used his iPad to watch football matches on their Christmas holiday in Morocco, running up a £10,935 data roaming bill. Matheson had initially claimed last month the bill was so large because he had not realised his sim card was out of date and no longer in contract, but insisted it was a legitimate parliamentary expense. Holyrood officials accepted his word, and agreed that £3,000 of that would be paid through his office expenses while the remainder would be funded by parliament. Matheson knew in February that £8,666 was incurred on 2 January. . The row again dominated first minister’s questions on Thursday, with the Conservative and Labour leaders repeating their calls for Matheson to be sacked. Douglas Ross, the Scottish Tory leader, said Matheson’s admission that the data was used by his children proved his original written assurances that it was used entirely on constituency work were “false” and had tried to “dupe” taxpayers. Humza Yousaf, the first minister, said the health secretary had rightly admitted he had made mistakes: “He did what he did to protect his teenage boys.” Matheson agreed to repay the full amount on Friday 10 November but without disclosing why. The following Monday he told reporters there had been no personal use of the iPad, but told Yousaf the next day his sons had used it to watch football. On Thursday 16 November he revealed to MSPs his wife had told him a week earlier his sons had admitted using his iPad at a hotspot to stream a match between bitter rivals Celtic and Rangers on 2 January. Anas Sarwar, the Scottish Labour leader, said there were now mounting examples of Yousaf’s government misleading MSPs, raising doubts about its honesty and integrity. The first minister had had to correct his own statements to parliament three times this year, Sarwar said, including his factually wrong claim that Scotland produced a majority of the UK’s renewable energy on a per capita basis. Yousaf insisted he took the ministerial duty to be truthful and accurate “very seriously”.