Neighbours of China's proposed 'super-embassy' have taken the first formal step in their bid for a judicial review of Labour's decision to approve it.
Residents of Royal Mint Court set out the grounds for their request in a pre-application letter to the UK government's legal department.
When the Chinese government bought 5.4 acres of the site in 2018, the purchase included the freehold to around 100 flats across four residential blocks.
These buildings lie outside the proposed perimeter for the embassy, but residents fear they could be evicted and their flats bulldozed to make space for a security wall.
They are also concerned about becoming targets for surveillance from the diplomatic complex, which would be China's biggest in Europe.
Beijing announced plans for its new embassy in 2018 after buying the former Royal Mint building for £250million.
Its first application was rejected by Tower Hamlets Council but it resubmitted its plan in July 2024, just weeks after Labour won the election, and soon afterwards president Xi raised the matter in a phone call with Sir Keir.
Just months later, Sir Keir told the president that his new Government would make the final decision after taking control of the planning process.
Housing Secretary Steve Reed approved China's proposal last month.
Residents of Royal Mint Court set out the grounds for their request in a pre-application letter to the UK government's legal department. Pictured is a concept for the embassy
In their pre-claim letter - seen by the FT - the residents of Royal Mint Court set out the grounds on which they believe the approval should be overturned.
They argue the approval is legally flawed, accuse the government of failing to disclose important security assessments and suggest Mr Reed's decision was 'improperly influenced by ministers' - including the desire for China to grant planning approval for an overhaul of Britain's embassy in Beijing.
They have also requested disclosure of documents and communications between the British government and China over the planning approval. Their bid for a judicial appeal is backed by £41,500 in crowdfunding.
The Prime Minister has been accused of giving up national security in return for a better trading relationship with Beijing, after Labour granted planning permission for the alleged spy base days before he flew out to meet president Xi Jinping.
In a sign of the espionage danger posed by what will be the biggest diplomatic mission in Europe, ministers admitted last month that action had been taken to 'increase the resilience' of nearby telecoms cables, which carry millions of pieces of sensitive data and sit just yards from the site at the old Royal Mint, near Tower Bridge.
And in a rare intervention, the heads of Britain's domestic intelligence agencies publicly warned they cannot eliminate the risk attached to the embassy, while Parliament's security committee said it had struggled to get answers about the controversial case.
A government spokesman insisted: 'National security is our first duty. Intelligence agencies have been involved throughout the process and an extensive range of measures have been developed to manage any risks.'
China's President Xi at the 20th CPC Central Commission for Discipline Inspection last month
The Government also published a letter to the Home Secretary and Foreign Secretary written by MI5 director general Sir Ken McCallum and GCHQ director Anne Keast-Butler.
They admitted: 'For the Royal Mint Court site, as with any foreign embassy on UK soil, it is not realistic to expect to be able wholly to eliminate each and every potential risk.'
But they added that MI5 had 'over 100 years of experience managing national security risks associated with foreign diplomatic premises in London', and that 'the package of mitigations deals acceptably with a wide range of sensitive national security issues, including cabling'.
In addition, they claimed there were 'clear security advantages' in China consolidating into one building the 'seven different diplomatically accredited sites' it currently operates across the capital.
Parliament's intelligence and security committee, which considered evidence from senior Whitehall officials as well as spy chiefs, also raised concerns about the planning process.
Its chairman, Labour peer and former minister Lord Beamish, said: 'It has proved more difficult than it should have been to get straightforward answers to our basic questions.'
He went on: 'We were surprised both at the lack of clarity as to the role that national security considerations play in planning decisions, and that advice was prepared without some of the key facts at hand.'
In the Commons, security minister Dan Jarvis revealed that 'an extensive range of measures have been developed to protect national security'.
The Mail on Sunday revealed that planning documents for the embassy included 'spy dungeons' (highlighted in red above) - two suites of basement rooms and a tunnel, with their purpose redacted for security reasons
He told MPs: 'We have acted to increase the resilience of cables in the area through an extensive series of measures to protect sensitive data.
'And I can confirm that, contrary to reporting, the Government had seen the unredacted plans for the embassy and the Government have agreed with China that the publicly accessible forecourt on the embassy grounds will not have diplomatic immunity, managing the risk to the public.'
Mr Jarvis acknowledged that China posed threats to UK security, ranging from cyber-attacks and espionage as well as transnational repression, but the minister insisted: 'It is only through engagement that we can directly challenge China on its malicious activity.'
Leading China critic Sir Iain Duncan Smith questioned the Government's claim that 'lawful embassy use' would not lead to interference with the cables, adding: 'Nothing about the Chinese is lawful here in the United Kingdom.'
And Labour's Alex Sobel warned: 'It will send a chilling effect through Tibetans, through Hong Kongers, through Uyghurs and other Chinese who just dissent with the regime in Beijing.'
Christopher Mung, who fled to Britain from Hong Kong, told a press conference in Westminster: 'This decision has struck fear into our hearts and make many regret taking up the UK's promise of our safety.'