Sir Keir Starmer has vowed to publish key evidence submitted by the Government as part of the collapsed China spy case and suggested the previous Tory administration was responsible for the trial failing to go ahead.
The Prime Minister said he intends to release the witness statements prepared by deputy national security adviser Matt Collins in full.
Kemi Badenoch's Conservative Party has been pressing ministers over their handling of the case into Christopher Cash, a former parliamentary researcher, and Christopher Berry after the trial collapsed.
Both men, who deny wrongdoing, were accused of passing secrets to the Chinese Communist Party in the UK.
They were charged under the Official Secrets Act, but the case against them was dropped last month as the government apparently refused to label China as a threat to UK national security.
Sir Keir said reviews written by the previous Conservative administration had been "carefully worded" not to describe China as an enemy.
He told Prime Minister’s Questions on Wednesday: "Instead, they stated increased national security protections where China poses a threat, and that the then government would engage with China to leave room open for constructive and predictable relations."
He added: "Under this Government, no minister or special adviser played any role in the provision of evidence.
"I can't say what the position was of the previous government in relation to the involvement of ministers or special advisers.
"If the Leader of the Opposition knows the answer to that question, and I suspect that she does, I invite her to update the House."
Kemi Badenoch responded to Sir Keir Starmer's statement by saying it "answers no questions".
The Conservative Party leader told the Commons: "Exactly as I expected, the Prime Minister had to be dragged out at the top of PMQs to give a statement that answers no questions."
She added: "It is simply unbelievable that he is trying to say the last government did not classify China as a threat."
Ms Badenoch referred to several comments made in 2021 and 2024, attributed to the previous Conservative government, and added: "In 2022, the director general of MI5 in November classified China as a threat in his remarks.
“How is it possible that the Government failed to provide the evidence that the [Crown Prosecution Service] needed to prosecute?"
Sir Keir replied: "The substantive evidence was provided in 2023 by the previous government. That is when the witness statement was submitted.
"I am going to disclose it, they will all be able to read it."
Sir Keir accused Ms Badenoch of "playing politics with national security", as the Tory leader said the alleged "spies were charged under a Conservative government - they were let off under Labour".
To protests from James Cleverly on the Opposition front bench, the Prime Minister also told the Commons: "The then foreign secretary sitting, over here [Mr Cleverly], one month after arrest, so absolutely the relevant time, gave a speech at Mansion House.
“It was called 'Our Position on China', setting out the government's policy.
“He said in that speech, summing up China as a 'threat' in one word would be, his words, 'impossible, impractical and most importantly, unwise'."
Sir Keir added: "It wasn't just him. The leader of the Opposition (Ms Badenoch) was business secretary at the time. In September '23, the leader of the Opposition said, her words, September '23, the relevant year, her words, 'we should certainly not be describing China as a foe'.
"It's worth looking up the word 'foe' in the dictionary."
The Prime Minister referred to comments which Ms Badenoch made in September 2024, when she said "I have shied away from calling China a threat", and added: "She is playing politics with national security."
Mrs Badenoch replied: "Let me finish that quote. At the end of that quote, that he just read out, I did describe China as a 'threat'.
“But this whataboutery that he is doing neglects the fact those spies were charged under a Conservative government - they were let off under Labour."
