Michael Gove declined to deny an incendiary report that Liz Truss’s personal phone was hacked by Russian spies, as the Government faced accusations of “ill discipline” and not taking national security “seriously enough”.

Mr Gove, who made a return to Cabinet this week as Levelling Up Secretary, insisted the Government has “very robust protocols” in place.

The Mail on Sunday reported that Kremlin agents who hacked Ms Truss’s phone while she was foreign secretary are thought to have gained access to sensitive exchanges with foreign officials on Ukraine, as well as private conversations with Kwasi Kwarteng.

Asked about the allegations, Mr Gove told Sky News’s Sophy Ridge on Sunday programme: “I don’t know the full details of what security breach, if any, took place.

“What I do know is that the Government has very robust protocols in place in order to make sure that individuals are protected, but also that Government security and national security are protected as well.”

He said he could not discuss national security matters, as “loose lips can sink ships when it comes to these questions”.

The newspaper also claimed details of the breach, apparently discovered when Ms Truss was running for the Tory leadership in the summer, were “suppressed” by then-prime minister Boris Johnson and Cabinet secretary Simon Case.

Mr Gove said: “I’m sure that Liz, both as foreign secretary and as prime minister, will have followed the advice that she was given by the intelligence and security communities.

“The more that we talk in detail about these things, the more that we risk giving information to people who wish this country and its citizens harm.”

Opposition parties have demanded an urgent investigation into the alleged attack.

Shadow home secretary Yvette Cooper said the claims raise issues around “cybersecurity … the role of hostile states, but also the allegations about whether a Cabinet minister has been using a personal phone for serious government business, and serious questions about why this information or this story has been leaked or briefed right now”.

The alleged phone hack, as well as the reappointment of Suella Braverman as Home Secretary just six days after she was forced out over a security breach, “raises wider concerns about the way in which the Government is not taking seriously enough these issues around national security”, said the Labour MP.