The Welsh first minister, Vaughan Gething, has expressed regret over the donations scandal that has beset his first weeks in office but rejected a fresh allegation that he may have committed perjury in statements made to the UK Covid inquiry concerning deleted messages. In an interview with the Guardian, Gething said it was important not to “get lost” in controversy that drew attention away from the business of running Wales and winning the general election. He vowed to show “resilience” in the face of attacks on him. Seven weeks into his leadership, Gething continues to face criticism for taking £200,000 from a company whose owner was convicted of environmental crimes, with Labour insiders warning the scandal is critically undermining his authority. Asked if he regretted taking the donation, Gething said: “I really do regret the impact it has had on so many people.” He said he was trying to draw a line under the issue by asking the Senedd’s standards of conduct committee to look at the issue of political donations and make sure they are “robust, transparent and have the confidence of the public”. Gething said he had followed the rules in accepting the donation and wanted to focus on the job of governing Wales and preparing for the general election. He said: “We’ve got to not get lost in a story that has importance but actually takes us away from our mainstream business.” This week, however, the pressure was ratcheted up by the emergence of an exchange with fellow Labour members from the time of the pandemic when Gething was health minister in which he said he was going to delete iMessages. He wrote: “I’m deleting the messages in this group. They can be captured in an FoI [freedom of information request] and I think we are all in the right place on the choice being made.” The UK Covid inquiry is considering whether to seek more information from Gething over the exchange, and a bereaved family support group expressed anger. In the Senedd on Tuesday, the Plaid Cymru leader, Rhun ap Iorwerth, suggested Gething may have committed perjury in his evidence to the inquiry when he addressed the issue of how information from the period was retained. Gething called the idea that he may have committed perjury “obnoxious”. He told the Guardian he had not deleted any messages that related to decisions made by the Welsh government during Covid. He said the iMessages, leaked to the news service Nation Cymru, related to “unkind comments” that were potentially embarrassing made on a group following a Labour group meeting. The first minister said: “This is actually about not saying things that are embarrassing as opposed to trying to hide Covid decision-making. I stand by everything I’ve said both about how my devices were managed [and] the information that’s been provided.” Asked if it was worrying that the messages had been leaked, he said: “It’s obviously concerning that a photo of a message from nearly four years ago has been provided to a journalist but that’s what happens and part of the job is you need to be resilient enough to deal with that.” He said there was “mischief” in how the messages had been presented and he had sent the full exchange to the UK Covid inquiry. Anna-Louise Marsh-Rees, of Covid-19 Bereaved Families for Justice Cymru, said: “Yet more obfuscation from Vaughan Gething. His explanations simply don’t stack up. He explained that the messages were just Labour group business. But if that was the case then FoI requests wouldn’t apply.” It is not the first time Gething has come under fire over Covid phone exchanges. During the Welsh leg of the inquiry in March, Gething blamed a “security rebuild” of his Senedd mobile phone for the deletion of WhatsApp messages from the time of the pandemic, calling it “a matter of real embarrassment”. Marsh-Rees said: “We must know why Welsh government didn’t disclose this [iMessage] group chat to the inquiry before the Cardiff hearing. It’s imperative that we have access these chats in their entirety.” The Welsh Conservatives said the “cloak and dagger decision-making in the Labour Welsh government” was clear to see. The former Welsh Labour minister Leighton Andrews said: “Every day there is a new story about the first minister. It’s distracting from the task of government and it’s highly damaging to the Labour party. All these issues involve questions of principle and of judgment.” The latest developments come as the Senedd celebrates its 25th anniversary and on Wednesday was voting on expanding the size of the parliament from 60 to 96 members and bringing in a new electoral system. Gething, who campaigned for devolution as president of NUS Wales, said the Welsh parliament’s successes had ranged from innovations in recycling and its organ donation opt-out law to its Flying Start programme for young children in disadvantaged areas and the launch of the Welsh development bank but he said devolution remained “fragile”.