LONDON — China’s intelligence services carried out “large scale espionage operations” that threatened the U.K.’s economy and security, a senior British government official told prosecutors in a collapsed alleged spying case that sparked a heated political row in Westminster.

Matthew Collins, the U.K.’s deputy national security adviser, said in written evidence released late Wednesday that the alleged activities of two men accused of spying for China were “prejudicial to the safety or interests of the UK,” and that “information and material” passed on by them would be “directly or indirectly” useful to the Chinese state.

But Collins also emphasized to prosecutors that the U.K. was committed to “pursuing a positive relationship with China to strengthen understanding, cooperation and stability,” according to the documents, which were published in response to mounting criticism about the government’s handling of the case.

Christopher Cash, 30, a former researcher for a Conservative MP, and Christopher Berry, a 33-year-old teacher, both denied allegations that they passed sensitive information to an alleged Chinese intelligence agent between 2021 and 2023. The Crown Prosecution Service unexpectedly dropped the charges against them last month, prompting a political backlash.

The U.K.’s director of public prosecutions said the case collapsed because evidence could not be obtained from the government referring to China as a national security threat. The opposition Conservatives, who were in power when the men were charged in April 2024, have blamed the current Labour government, claiming it was “too weak to stand up to Beijing on a crucial matter of national security.”

In an unusual move, the government on Wednesday evening published three witness statements provided by Collins to the CPS between December 2023 and August 2025.

In the most recent statement, Collins said that Chinese intelligence services are “highly capable and conduct large scale espionage operations against the UK to advance the Chinese state’s interests and harm the interests and security of the UK. China’s espionage operations threaten the UK’s economic prosperity and resilience, and the integrity of our democratic institutions.”

However, Collins also emphasized that the U.K. government is committed to seeking a “positive” relationship with Beijing. Its position was to “co-operate where we can; compete where we need to; and challenge where we must, including on issues of national security,” he said.