Unveiled construction plans for China’s new expansive embassy in London have sparked a wave of national security concerns across the United Kingdom. The blueprints, recently made public, disclose the presence of an underground chamber situated alarmingly near some of Britain’s most critical communication cables.

Critics have raised alarms over the proposed embassy’s proximity—just a meter away—to crucial internet infrastructure. They caution that the concealed room might be intended for espionage activities by China. Although the British government has reportedly assured its allies that these cables do not carry sensitive government information, they are integral to financial transactions and communications for millions of internet users.

The plans were unredacted on Monday by The Telegraph, just a week before Prime Minister Keir Starmer is expected to greenlight the project ahead of his planned visit to China to meet President Xi Jinping.

A government spokesperson addressed the concerns, stating, “National security is our foremost responsibility, and government security experts have been actively involved throughout the process.”

Protests have erupted against the proposed Chinese embassy at the Royal Mint Court in London. (Photo by Matthew Chattle/Future Publishing via Getty Images)

According to the blueprint, the facility will be located at the former Royal Mint and will become Europe’s largest Chinese embassy. 

Construction plans indicate that China intends to demolish and rebuild a basement wall, placing officials and equipment just over three feet from critical fiber-optic cables. Security experts have warned that such proximity could create opportunities for “cable-tapping,” which involves inserting wiretaps or reading light signals leaking from the lines.

Professor Alan Woodward, a security expert at the University of Surrey, highlighted the technical feasibility of espionage given the physical layout, The Telegraph reported. He described the demolition as a “red flag” and noted, “If I were in their shoes, having those cables on my doorstep would be an enormous temptation.”

Royal Mint Street at the rear of the possible future Chinese embassy which has been locked in a planning battle for years and whose decision is still due for review, on 10th June 2025, in London, England (Richard Baker/In Pictures via Getty Images)

Additionally, the concealed chamber appears to be equipped with at least two hot-air extraction systems designed to ventilate heat-generating equipment. Experts reportedly inferred that this infrastructure suggests that the room is designed to accommodate high-powered technology such as advanced computers typically used for espionage and data processing. 

Beyond the single chamber near the cables, the unredacted plans also revealed a network of 208 secret rooms beneath the diplomatic site. The basement appears to allow for emergency backup generators, sprinkler systems, communications cabling and showers, suggesting that officials could remain underground for extended periods, potentially to operate or monitor equipment.

The construction plans have generally raised fears that the London complex could serve as a Beijing intelligence hub. According to U.K. outlet The Times, Britain has been pressured to reassure the United States and other intelligence partners that the cables do not transmit any sensitive government data.

Protesters hold a huge banner saying “No To China’s New Mega Embassy Spy Base In London’ during the demonstration outside the Royal Mint on March 15, 2025. (Martin Pope/SOPA Images/LightRocket via Getty Images)

Alicia Kearns, the shadow national security minister and prominent critic of the project, described the approval of the embassy as handing Beijing a strategic advantage against British interests.  

“Giving China the go-ahead for its embassy site would be to gift them a launchpad for economic warfare at the very heart of the central nervous system of our critical financial national infrastructure,” she said in a post on X.