A petition to stop US President Donald Trump’s UK state visit has gathered more than a million signatures.
Numbers of signatories have been rising rapidly since a US clampdown on immigration came into effect over the weekend, causing anger worldwide.
PM Theresa May announced the visit during her recent US trip. Downing Street has rejected calls for it to be cancelled as a “populist gesture”.
Labour’s Jeremy Corbyn urged the PM to postpone the visit.
Graham Guest, a solicitor from Leeds who began the petition, said he wanted it to “put the spotlight” on Mr Trump.
On Sunday, he told the Press Association news agency: “A state visit legitimises his presidency, and he will use the photo opportunities and being seen with the Queen to get re-elected.”
On Friday Mr Trump signed an executive order halting the US refugee programme for 120 days, indefinitely banning all Syrian refugees and suspending the entry of all nationals from seven Muslim-majority countries.
Moves to implement the measure triggered anger and protest across the world.
On Saturday afternoon the petition had just 60 signatures but reached 100,000 needed to be considered for debate by Parliament just after midday on Sunday.
MPs will discuss the debate on Tuesday.
Protests in response to Mr Trump’s executive order are expected to take place after 18:00 in London, Manchester, Bristol, Brighton, Liverpool, Glasgow, Edinburgh, Cardiff and Swansea.
Buckingham Palace has declined to comment on the row.
The Downing Street source told the BBC an invitation had been “issued and accepted” and scrapping it would “undo everything” following Mrs May’s visit.
“America is a huge important ally. We have to think long term,” the source added. No date has been set for the state visit.
But Shadow Attorney-General Shami Chakrabarti said the government’s position “sounds like appeasement”.
Mr Corbyn, who is supporting the petition, tweeted: “@Theresa_May would be failing the British people if she does not postpone the state visit & condemn Trump’s actions in the clearest terms.”
“@realDonaldTrump should not be welcomed to Britain while he abuses our shared values with shameful #MuslimBan & attacks on refugees & women,” he added.
Alex Salmond, the SNP’s foreign affairs spokesman, said he thought the state visit was “a very bad idea”.
And Mayor of London Sadiq Khan said the visit should not happen while the executive order was in place.