MI5 chief reveals China plot was foiled last week - as he warns Beijing poses threat to Britain amid spy case row

Ken McCallum said he would “never back off” from confronting threats from China, which he said posed a national security threat “every day”.

He added: “Of course I am frustrated when opportunities to prosecute national security-threatening activity are not followed through. 

“My teams have every right to feel proud of the detection and disruption job they have done in this case.”

He also revealed that MI5 directly foiled a plot by Beijing in the past week, but refused to give further details. It is understood this was not related to Parliament.

It comes after the case was dismissed because the Government refused to label Beijing a threat.

This let alleged spies Christopher Berry and Christopher Cash, who both denied wrongdoing, walk free from court.

Read more: China - UK spy scandal timeline as accusations deepen

Read more: Key witness in spy case said UK wanted ‘positive relationship’ with China despite Beijing being branded a 'threat'

The teacher and former parliamentary researcher were accused of passing secrets to China between 2021 and 2023, but charges against them were dropped last month. 

This sparked backlash against the Government, which had been accused of a cover-up over the affair, and a furious row between the Cabinet and the Crown Prosecution Service (CPS).

Pressure mounted on Sir Keir Starmer, who last night released witness statements from the trial after Kemi Badenoch’s Conservative Party hounded ministers over their handling of the case.

One statement from civil servant Matthew Collins, the deputy national security adviser, declared the UK wanted a “positive relationship” with Beijing, his published statements revealed. 

In the documents, Beijing is repeatedly called a threat, despite suggestions that the government's inability to do so.

In one passage, Mr Collins says: "China...presents the biggest state-based threat to the UK's economic security".

He also revealed that the UK's "democratic institutions and parliamentarians" including the Electoral Commission had suffered "large-scale espionage campaigns" by Chinese-state affiliated people and organisations in recent years.

MI5 chief Mr McCallum backed Mr Collins following the release of his statement.

“I do consider him to be a man of high integrity and a professional of considerable quality,”  Mr McCallum said.

He also endorsed a statement by former National Cyber Security Centre chief Ciaran Marti, which said that “highly classified state secrets” had not been accessed by China.

Another statement released under Labour insisted the Government was "committed to pursuing a positive economic relationship with China".

Sir Keir has repeatedly rejected allegations of wrongdoing on the part of the Government. He has blamed the collapse of the trial on the Conservatives’ approach to China in power.

The Prime Minister said the last Tory government “declined to describe China either as an enemy or infer that by describing it as a current threat to national security”.

The party’s foreign affairs spokesperson Calum Miller said: “If ministers have nothing to hide they have nothing to fear.

“Failure to come clean will just confirm people’s suspicions of a cover-up and that ministers are more worried about cosying up to China than protecting our national security.”