China breached high level security systems to obtain “vast amounts” of classified government information over a period of many years, Dominic Cummings has claimed.
Boris Johnson’s former adviser said he and the then-prime minister were told about the breach in 2020 and that it involved so-called Strap material, a government classification for highly sensitive intelligence material.
He said that fundamental infrastructure for transferring sensitive data around the British state was compromised “for years”.
He did not say how the system had been breached but that he would be willing to share what he knew with MPs if they were to hold an inquiry.
It comes amid serious questions over national security and government policy towards China after the abandonment of China spying case trial. The case against Christopher Cash, 30, a former parliamentary researcher, and Christopher Berry, 33, a teacher, was dropped this year.

Mr Cummings told The Times: “What I’m saying is that some Strap stuff was compromised and vast amounts of data classified as extremely secret and extremely dangerous for any foreign entity to control was compromised.
“Material from intelligence services. Material from the National Security Secretariat in the Cabinet Office. Things the government has to keep secret. If they’re not secret, then there are very, very serious implications for it.”
Earlier on Wednesday, at the start of Prime Minister’s Questions, Sir Keir Starmer promised to publish key evidence that forms part of the collapsed China spying case.
Three witness statements that were shared with prosecutors would be published, said Sir Keir, as he maintained his position that the previous government is to blame for the failure to prosecute.
The Crown Prosecution Service has said the case collapsed because the government’s evidence did not show that China represented a threat to national security at the time of the alleged offences.

But Sir Keir insisted the “substantive” evidence was submitted under the Conservatives and supplementary statements handed to the CPS subsequently reflected the Tory administration’s position.
Mr Cummings called it “absolutely puerile nonsense” to suggest that whether to define China as a threat is a “difficult semantic question”.
“Anyone who has been read in at a high level with the intelligence services on China knows that the word threat doesn’t even begin to cover it,” he said.
The Cabinet Office has been approached for comment.