UK Prime Minister David Cameron has ignored calls to apologise to Republican presumptive presidential nominee Donald Trump for referring to him as "stupid" and "divisive".

Trump's advisor said that as the billionaire is now the likely GOP nominee, Cameron should apologise for comments made during a debate over banning the Republican from the UK over his suggestion of preventing Muslims entering the US.

Despite voting against a travel ban on Trump, Cameron told parliament: "I think his remarks are divisive, stupid and wrong. If he came to visit our country I think he would unite us all against him."

At the time the remarks were made, Trump was already dominating the Republican race for the nomination, but with his presidential candidacy almost certain, his advisor George Papadopoulos said it would be wise for Cameron to extend the hand of friendship.

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Papadopoulos told The Times: "I can't speak directly for him but it would seem that if Prime Minister Cameron is serious about reaching out, not only to Mr Trump's advisers but to the man himself, an apology or some sort of retraction should happen.

"To see Mr Cameron come out as the most vocal opponent was uncalled for. Considering that we believe that the UK-US relationship should be a cornerstone, not just of Nato policy but elsewhere, it would be wise for him to reach out in a more positive manner to Mr Trump."

The advisor did add that any invitation would be "a show of untiy" and "a wonderful spectacle", adding that an invite to the UK would be warmly welcomed by Trump.

But for his part, Cameron is not intending to address the issue any time soon, and does not appear to be issuing an apology.

Mr Cameron's spokeswoman said in a statement: "The PM has no intention of withdrawing his comments, which were made in response to comments that Donald Trump made calling for a ban on Muslims entering the US. That was the context for the PM's comments."