"He will depart for his travel to China and Japan on Tuesday night," the Downing Street spokesman told reporters on Monday.

The visit will be at the heart of Starmer's ambition to reset ties with China, an economic powerhouse, after relations between London and Beijing sank to new lows under the previous Conservative government.

The announcement of his trip comes less than a week after the British government approved contentious plans to build a "mega-embassy" in the heart of London.

The 20,000-square-metre (235,000-square-foot) site is set to become the largest embassy complex in the UK by area, and one of the largest in the centre of a Western capital.

But it could still face legal challenges and angry residents vowed last week to act.

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

Housing minister Steve Reed's decision on January 20 to grant planning permission for the new embassy came after several delays over national security concerns.

There have also been protests by activists who fear the sprawling site could be used to spy on and harass dissidents.

A government spokesperson said intelligence agencies had helped to develop a "range of measures ... to manage any risks".

"Following extensive negotiations in recent months, the Chinese government has agreed to consolidate its seven current sites in London into one site, bringing clear security advantages," the spokesperson said.

Security minister Dan Jarvis said China would continue to pose national security threats.

Asked whether the UK leader would also raise the issue of Chinese ownership of British steel during his talks, his spokesman said Tuesday "clearly you can expect a range of issues to be raised, including but not restricted to trade and investment".