Downing Street on Monday did not comment on reports that Liz Truss’s personal mobile phone was hacked by Russian agents while she was foreign secretary, insisting only that a “robust” approach is taken to protect ministers’ data.

The story emerged in the Mail on Sunday, prompting concerns about information security and questions about the use of personal mobile phones by ministers.

The Prime Minister’s official spokesman said that it is “longstanding policy not to comment on security matters” and declined to discuss individual security arrangements.

“Ministers do receive regular security briefings including advice on protecting their personal data and mitigating cyber threats and we do have robust systems in place to protect against those threats,” he told reporters.

The spokesman also said that Prime Minister Rishi Sunak adheres to that advice, while refusing to be drawn on whether the UK’s allies had been informed about any security breach.

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

Earlier, environment minister Mark Spencer said Ms Truss “clearly was hacked” but suggested all ministers used personal phones even if there was “some little man in China” listening in.

“We all talk on personal phones, don’t we, you know? I ring my wife, maybe there’s some little man in China listening to the conversations between me and my wife.

“But, you know, you’ve just got to be careful about what information you use on which phone and you get a lot of help and support from the security services on that.”