Starmer arrived on Wednesday for the first visit by a British prime minister to China since 2018, seeking to promote what he called "pragmatic" partnership with the Asian giant after years of fraught relations.

The issue of irregular migrants is highly sensitive for the Labour leader, who has promised to crack down on people smugglers and stem a wave of arrivals that has fuelled rising support for the far-right.

Last year, nearly 42,000 migrants landed on England's southern coast after making the perilous Channel crossing from northern France -- the second-highest annual number.

"More than half of small boat engines used by people smugglers crossing the English Channel are manufactured in China," a statement from Downing Street said, as Starmer is set to hold talks with Chinese President Xi Jinping.

The two leaders are due to meet for lunch in Beijing on Thursday, when Starmer will also sit down with Premier Li Qiang.

The agreement to be signed calls for intelligence sharing and "direct engagement with Chinese manufacturers" of boat parts to ensure they are not "being exploited by organised crime", the statement said.

The deal also seeks to boost cooperation on combatting the trafficking of "highly potent and dangerous synthetic opioids such as nitazenes, known to be produced in China and exported to the UK", it added.

On Wednesday, Starmer told a delegation of around 60 business leaders and cultural representatives accompanying him that "it is in our national interest to engage with China."

He urged them to seize the "opportunities" offered by China and said the visit was "making history".

"You're part of the change that we're bringing about," Starmer said.

The trip has been lauded by Downing Street as a chance to boost trade and investment ties while raising thorny issues such as national security and human rights.

Starmer follows a string of Western leaders courting Beijing in recent weeks, pivoting from a mercurial United States.

Britain has faced a rift with its closest ally following President Donald Trump's bid to seize Greenland and his brief threat of tariffs against the UK and other NATO allies.