The information watchdog has launched an official investigation into the use of private email accounts at the Department of Health and Social Care (DHSC) following reports over Matt Hancock's conduct.
The Information Commissioner Elizabeth Denham said her office had served notices on the department to preserve evidence relevant to her inquiry.
Last week reports emerged Matt Hancock and current minister Lord Bethell had routinely used private email accounts to discuss government business.
It followed the scandal that forced Mr Hancock to resign as health secretary, after he was caught kissing a government aide - breaking Covid regulations.
In a blog posted on the Information Commissioner’s Office’s website, Ms Denham said the use of private communications channels was not in itself a breach of the rules, she was concerned that it could be used to frustrate the freedom of information process.
"My worry is that information in private email accounts or messaging services is forgotten, overlooked, autodeleted or otherwise not available when a freedom of information request is later made," she said.
"That is why my office has launched a formal investigation into the use of private correspondence channels at the DHSC, and has served information notices on the department and others to preserve evidence relevant to my inquiry."
The Lords Commissioners for Standards has also announced they are investigating Lord Bethell over a complaint that he sponsored a parliamentary pass for Gina Coladangelo - the aide caught in an embrace with Mr Hancock on leaked CCTV footage.
A long-term friend of Mr Hancock, Ms Coladangelo was brought into the DHSC first as an unpaid adviser before being made a non-executive directors receiving £15,000-a-year for three days work.
Members of the House of Lords can sponsor passes for secretaries and research assistants if they “genuinely and personally” fulfil those roles for the sponsoring member.
The sponsor has to sign a declaration to that effect, and it would be against the rules if the individual did not work for the peer.
Passholders have free access to the Palace of Westminster, where they can mingle with ministers and MPs and use the estate’s facilities such as bars and restaurants.
Ms Coladangelo is no longer listed as a member of staff for Lord Bethell on his parliamentary web page.
But an online archive showed she was listed as a staff member in May last year as “Mrs Gina Tress”, a marketing and communications director for Oliver Bonas, the retailer founded by her husband, Oliver Tress.”
Labour said it welcomed the investigation into the use of private emails, with Deputy Leader Angela Rayner calling on the government to "cooperate fully."
"Labour welcomes this important investigation and the government must cooperate fully, turning over all correspondence, emails and documents.
"The government cannot be allowed to cover up dodgy dealings with taxpayers’ money being handed out to friends of Ministers.
"What is important now is getting to the bottom of how far this shady practice extends across the government, and ensuring that the Covid public inquiry has access to all evidence."
At the time reports emerged over Mr Hancock's potential use of personal emails, the prime minister’s official spokesperson said: "Both the former health secretary and Lord Bethell understand the rules around personal email usage and only ever conducted government business through their departmental email addresses."
The spokesperson suggested Mr Hancock’s use of a Gmail account was "related to things like diary acceptances".
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