Britain’s main opposition leader Kemi Badenoch joined a protest on Saturday against China’s planned “mega embassy” in London, with a government deadline approaching to approve or block the project.

Demonstrators gathered near the former Royal Mint site by Tower Bridge and chanted “no China mega embassy” as opposition politicians addressed the rally.

Badenoch urged the Labour government to reject the plans, saying the Chinese government had “harassed and sanctioned” members of Parliament and “abused British nationals connected to China.”

“We know that we have to stand up to the abuses of China. And what worries me is that we have a government right now that seems to be scared of China,” Badenoch told the crowd.

The government has set a deadline of Tuesday to decide whether to approve plans for what it would be the largest Chinese embassy in Europe. The project is slated for the Royal Mint site near Tower Bridge, after years of delays and legal challenges.

While the development is expected to get approval, China has complained about the seven-year delay in approving the project, saying the U.K. was “constantly complicating and politicizing the matter.”

Prime Minister Keir Starmer said protecting national security is nonnegotiable, while also saying Britain needs to keep up diplomatic dialogue and cooperation with China.

Starmer’s office has linked approval of the embassy to diplomatic outcomes, saying it would pave the way for a long-anticipated trip by Starmer to China and an expansion of the U.K. Embassy in Beijing.

Opponents of the project argue that the embassy complex—planned to cover 20,000 square meters (215,000 square feet)—could be used as a base for espionage, and for the surveillance and intimidation of Chinese dissidents in exile. They point to the site’s proximity to London’s financial district and to crucial data cables.

The debate has also been shaped by warnings within Britain’s intelligence community. The MI5 domestic intelligence agency issued an alert to lawmakers in November warning that Chinese agents were making “targeted and widespread” efforts to recruit and cultivate them using LinkedIn or cover companies.

Britain’s security services are thought to have OK’d the embassy development, and some security experts have said the risks are manageable. They said the embassy would also consolidate China’s current seven diplomatic premises in London into one location.

Ciaran Martin, the former head of Britain’s National Cyber Security Centre, wrote that no British government would override the security services if they said the project was too risky. “Unless we want to sever diplomatic relations with China, the location of their embassy becomes an issue of practicalities, security assessments and counterintelligence operations,” he wrote in The Times of London.