The Scottish government has been ordered to release all its WhatsApp messages from during the coronavirus pandemic after it failed to disclose them to the UK Covid inquiry. The inquiry heard on Thursday that none of the private messages written during the Covid crisis by Nicola Sturgeon, who was then first minister, or by her health and finance ministers, had been disclosed despite repeated requests dating to 2022. Jamie Dawson KC, the Scottish counsel to the inquiry, said there were suggestions these messages had been deleted, potentially in breach of the rules on retaining government records. His intervention sparked a heated row at Holyrood where Humza Yousaf, the first minister, was challenged by Douglas Ross, the Scottish Conservative party leader, to explain why the devolved government had failed to disclose any messages. If they had been deliberately withheld “it would be a shocking display of secrecy, it would potentially break the law”, said Ross. Yousaf denied there had been an attempt to withhold material and said that morning he had appointed Ruth Charteris KC, the Scottish government’s solicitor general, to investigate. Yousaf said he, his ministers and his officials were aware of their legal duties to retain that information and knew they were bound by a “do not destroy” policy. “I can give an absolute assurance to those families listening, where we hold any relevant information that will be passed on,” he said. This row has strong echoes of the long-running dispute between the Scottish government and a special Holyrood committee set up to investigate the inquiry into alleged sexual misconduct by the former first minister Alex Salmond in 2020. There were repeated arguments between MSPs on the committee and Sturgeon’s, deputy, John Swinney, over the failure to find and then release government papers, culminating in a legal battle over disclosure of the government’s legal advice. Speaking on Thursday morning, Dawson said it appeared that 137 messaging groups had been used during the pandemic, with the conduct of about 70 Scottish witnesses now under scrutiny, including officials at Public Health Scotland agency. The inquiry had struggled to understand what the government’s policies and practices were, because its replies to the inquiry’s requests for information, about who used these messaging apps and how, were incomplete or vague. He said that three weeks ago the Scottish government suddenly said it needed a formal order under section 21 of the Inquiries Act 2005 before it could release this kind of information, because of data privacy concerns. “The inquiry expects that what has ultimately been provided to us by the Scottish government comprises the full disclosure which the first minister promised would be provided,” Dawson said. “If it transpires that this is not the case, the inquiry will wish to know why.” Dawson said the inquiry “intend to keep an open mind” about the content of those messages but said it was surprising so much had been destroyed when the UK government’s WhatsApp messages were largely retained. “A clear theme of the overall response received from and via the Scottish government is that although such messaging systems were used in the pandemic response, including by some key decision-makers and others, generally very few messages appear to have been retained,” he said. “This is surprising, in particular in light of the apparent availability of such messages in high volumes within the UK government.” Aamer Anwar, the solicitor for the Scottish Covid Bereaved group, which is a formal participant in the inquiry, described Dawson’s disclosures as “devastating”. He said: “The families we represent deserve the truth. The Scottish Covid bereaved find it inconceivable that the most senior figures in the Scottish government from Sturgeon, Swinney, and [finance secretary] Kate Forbes, to the present first minister, Yousaf, failed to retain their WhatsApp messages over the two-year period of the pandemic.”