The remarks of US President Donald Trump on the unification of Ireland and Britain's Northern Ireland have sparked strong opposition from Britain.

During a two-day visit to Ireland, Trump said on Saturday he would "love to see" the unification of Ireland and Britain's Northern Ireland.

"President Trump is shooting from the hip as usual, just like he did with Greenland and Canada becoming the 51st state," said Conservative Party leader Kemi Badenoch on X on Saturday.

She added that "Northern Ireland is part of the United Kingdom."

"I disagree with President Trump," said Reform UK leader Nigel Farage on X the same day, "Northern Ireland is a proud and integral part of the United Kingdom."