A decision on whether to approve China’s application for a new super-embassy in London has been delayed again by the government.

Housing Secretary Steve Reed had been due to rule on the application by 21 October, but the deadline has been pushed back to 10 December.

It is the second time the government has delayed a decision on the controversial site, whose location has sparked concerns it could pose an espionage risk.

A ruling had originally been due by 9 September after ministers took control of the process from Tower Hamlets, the local council, last year.

China bought the site of the proposed new embassy, at Royal Mint Court, near the Tower of London, for £255m in 2018. At 20,000 square metres, the proposed complex would be the biggest embassy in Europe if it goes ahead.

The pending decision on whether to approve the new embassy was already under close scrutiny because of concerns about the security implications of the plan, including the location, size and design of the building.

The site is close to fibre optic cables carrying communications to and from financial institutions in the City of London. Concerns have been raised that Chinese operatives could use the site to tap into the cables and eavesdrop.

Further questions have been raised in recent weeks about the nature of the threat posed by Beijing, following the collapse of the case against two men accused of spying for China.

The Crown Prosecution Service (CPS) unexpectedly dropped charges against parliamentary researcher Christopher Cash, 30, and academic Christopher Berry, 33, last month. Both men deny the allegations.

The government’s first delay was requested by Reed’s predecessor Angela Rayner, after she asked China to explain why some rooms within its planning documents had been blanked out for “security reasons”.

Planning consultants working for the Chinese embassy had replied that China “does not consider that, as a matter of principle, it is necessary or appropriate to provide full internal layout plans”.

Rayner had written back to groups involved in the consultation, including China, the Met police and a local residents’ association, to give them more time to respond to the plans and putting the deadline back to 21 October.

Reed, who took over the housing role following Rayner’s resignation last month, has now requested additional time before a final decision needs to be made.

In a letter seen by the BBC, the housing department said more time was needed due to the “detailed nature” of responses received so far.

It added that it was unable to set a new deadline for fresh comments until it receives pending responses from the Foreign Office and Home Office.

The proposed complex would include offices, a large basement area, housing for 200 staff, and a new tunnel to connect the Embassy House to a separate building on the embassy grounds.

Beijing’s application for the embassy was initially rejected by Tower Hamlets Council in 2022 over safety and security concerns.

It resubmitted an identical application to the council in August 2024, one month after Labour came to power. The government then took over the decision in October.

The Chinese Embassy in the UK has previously said the new complex would enhance “mutually beneficial cooperation” between China and Britain.

In a new diplomatic note released alongside Reed’s letter explaining his reasons for the latest delay, a Chinese official said objections to the site were “either ill-founded or unjustified”.

The Conservatives said Labour ministers should throw out the application, and accused them of trying to “silence the warnings about the threats to national security” posed by the embassy site.

The Liberal Democrats also called for the application to be blocked, calling on the government to “stand up to China”.

Foreign Affairs spokesperson Calum Miller said it would be “insane” for ministers to allow the embassy development to go ahead, after warnings from the head of MI5 on Thursday about the threat of Chinese espionage.

Boris Johnson’s former chief advisor Dominic Cummings said MI5 and MI6 had warned him China was “trying to build a spy centre underneath the embassy,” when he was working at Downing Street.

Speaking on ITV’s Talking Politics podcast, Cummings said the agencies had told him that allowing the embassy to be built would be “an extremely bad idea”.

In his annual speech, Sir Ken McCallum said “Chinese state actors” presented a national security threat to the UK “every day”.

He added that the UK needed to “defend itself resolutely” against China, while also being able to “seize the opportunities” from having a relationship with Beijing.