Beijing's proposal for a new embassy on the historic site of the former Royal Mint -- a stone's throw from the Tower of London -- has been dogged by delays since China bought it in 2018.

If the relocation from its current site in London's upmarket Marylebone area is approved, it would be the largest embassy complex in the UK by area, and one of the largest embassies in the heart of a Western capital.

But the move has faced fierce opposition from residents, rights groups and critics of China's ruling Communist Party who fear the site could be used to surveil and harass dissidents.

The embassy proposal has proved to be particularly sensitive domestically, and appears to be a sticking point in bilateral ties as well.

The UK's plans to redevelop its own embassy in China are also reportedly being held up.

Starmer is expected to visit China later this month, according to British media -- although the trip has not yet been confirmed by Downing Street -- as he tries to reset ties with the economic powerhouse.

If it goes ahead, it would be the first visit by a UK prime minister since 2018, after ties between London and Beijing fell to new lows under the previous Conservative government.

But the embassy plans, along with domestic furore over a collapsed case against two British men accused of spying for China and the conviction of media mogul and British citizen Jimmy Lai in Hong Kong on two national security charges, could make for an eventful first visit for Starmer.

While UK media reported that the development is likely to receive the green light this week, a refusal would not go down well in China.

When the decision was postponed once again in December, Chinese foreign ministry spokesman Lin Jian said Beijing was "deeply concerned" and "strongly dissatisfied".

Meanwhile, Starmer last month acknowledged that while China provided significant economic opportunities for the UK, it also posed "real national security threats".

- 'Spy embassy' -

Last week, The Daily Telegraph reported the new embassy site would house 208 underground rooms, including a "hidden chamber", according to unredacted plans obtained by the newspaper.

The vast site would also run alongside sensitive underground internet cables, with the unredacted plans showing that Beijing would demolish and rebuild a wall between the cables and the embassy.

The high-speed internet cables connect to the City of London financial district, with the Telegraph raising concerns that they could be tapped underground.

Hundreds rallied against the impending decision outside the proposed site on the weekend.

"We cannot allow the Chinese to build this spy embassy in an area so crucial to our national security," said opposition Conservative party leader Kemi Badenoch.

A protester in London who gave his name only as Brandon, for fear of reprisals, told AFP on Saturday that the plans raised a "lot of concerns".

"I don't think it's good for anyone except the Chinese government," said the 23-year-old bank employee, who moved to the United Kingdom from Hong Kong.

Clara, a protester also originally from Hong Kong, said she was "really afraid of transnational repression that China can impose on us."

The head of the Inter-Parliamentary Alliance on China, Luke de Pulford, said the government would face an "embarrassing and potentially catastrophic" legal challenge from local residents if the plans were approved.