The government is facing calls for an investigation into newspaper allegations that a personal phone used by Liz Truss while she was foreign secretary was hacked by foreign agents suspected of working for Russia.
The government has refused to comment on the reports that private messages between Truss and foreign officials — including discussions on Ukraine — could have fallen into the hands of the Kremlin.
The opposition Labour party said the reports raised “immensely important national security issues”.
According to the Mail on Sunday the hack was discovered during the summer while Truss was foreign secretary and was contesting the Tory leadership contest, but the news was suppressed by politicians and civil servants.
The paper said that then-prime minister Boris Johnson and cabinet secretary Simon Case agreed there should be a news blackout.
“It is not a great look for the intelligence services if the foreign secretary’s phone can be so easily plundered for embarrassing personal messages by agents presumed to be working for Vladimir Putin’s Russia,” one person with knowledge of the situation told the newspaper.
The government said it “did not comment on individuals’ security arrangements” and had “robust” cyberthreat protection in place. Ministers are given briefings by the security services on such issues.
Yvette Cooper, shadow home secretary, said: “There are immensely important national security issues raised by an attack like this by a hostile state, which will have been taken extremely seriously by our intelligence and security agencies.
“There are also serious security questions around why and how this information has been leaked or released right now, which must also be urgently investigated.”
The messages that fell into foreign hands included personal conversations between Truss and Kwasi Kwarteng, her future chancellor, according to the report. It cited sources who said that up to a year’s worth of messages had been compromised and they were believed to have included highly sensitive discussions with other foreign ministers overseas about the war in Ukraine.
Earlier this month, Suella Braverman was sacked as home secretary by Truss after she admitted using a private email account to send confidential cabinet papers to a colleague. She was later reinstated by the new prime minister Rishi Sunak.
Layla Moran, Liberal Democrat foreign affairs spokeswoman, said: “We need an urgent independent investigation to uncover the truth. If it turns out this information was withheld from the public to protect Liz Truss’s leadership bid, that would be unforgivable.”