Protesters rallied outside parliament as MPs debated a petition to cancel a state visit by Trump, which gained more than 1.8 million signatures.
The UK government on Monday defended its decision to offer US President Donald Trump a lavish state visit and an audience with the queen this year.
"In the light of America's absolutely pivotal role, we believe it entirely right that we should use all the tools at our disposal to build common ground with President Trump," junior foreign minister Alan Duncan told parliament.
He described state visits as Britain's "most important diplomatic tool", saying Trump's trip would go ahead as planned.
The statement came as MPs debated a petition to cancel a state visit by Trump, which gained more than 1.8 million signatures.
Coinciding with the debate, thousands demonstrated outside the parliament against Trump's visit.
Placards reading "No to Trump" and "Dump Trump" were held by demonstrators in Parliament Square, in the latest rally against the US president who came to power a month ago.
TRT World's Simon McGregor-Wood reports from London.
‘Desperate' for trade deals
Prime Minister Theresa May's government wants to reaffirm the "special relationship" with the United States and secure a trade deal as Britain prepares to leave the European Union.
Lawmakers also discussed a counter-petition to uphold the state visit invite, which attracted over 300,000 signatures.
During the debate, opposition Labour MP David Lammy said the government offered the state visit because it is "desperate" for a trade deal with the US.
"I think my children deserve better than that … I'm ashamed that it's come to this," he said.
Fellow Labour lawmaker Paul Flynn said the invitation should be downgraded from the regal affair to a regular visit.
While Trump was offered a state visit after just seven days in office, his predecessor Barack Obama had to wait 758 days before receiving the same invitation.
Since taking office in January, Trump has sparked global protests over plans to ban immigrants from seven Muslim-majority countries, and from women activists who call him misogynistic.
‘Promoting racist polices'
Outside parliament, protester Benjamin Kari said people needed to stand up against Trump's policies and avoid becoming complacent.
"He's promoting racist policies, he's normalising racism and misogyny and Islamophobia," he said.
Bryan Richardson, a member of the Stand up to Racism group, said May "humiliated herself by rushing over to Washington to be the first leader to meet Donald Trump."