Donald Trump calls for united Ireland, sparking immediate political backlash

Donald Trump has triggered a diplomatic row after backing a united Ireland during a visit to Dublin, wading into a politically sensitive subject as he embarked on a two-day Irish visit that blurs the lines between his presidency and personal business interests.

Speaking to reporters on Saturday, the US president claimed Irish reunification was inevitable, adding it "may as well happen now".

His comments brought a stern rebuke from the Conservatives in the UK while Downing Street pointed to Prime Minister Andy Burnham's rejection of an immediate border poll earlier in the week.

"I'd love to see it unified. I think it would be a great feather in everybody's cap if that happened. It's going to happen eventually," Trump said, answering a question from the Press Association.

Referencing Irish Taoiseach, Micheál Martin, sitting next to him, Trump added: "We're talking about it and you got the right man over here to get it moving."

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"But, yeah, I think it would be a fantastic thing... Now the UK will have something to say about it, obviously. But I think it would be a great thing. I mean, how can it be bad?"

The United States has previously adopted a neutral position on the issue, with the island of Ireland split between the Irish republic in the south and Northern Ireland — which is part of the United Kingdom — since 1921.

The comments are likely to further strain relations between the US and the UK, with Trump also casting doubt on Britain's ability to defend the Falkland Islands during the visit.

On Wednesday, Burnham told MPs a border poll would only be considered when there was "a clear consensus in the country".

Asked about Trump's comments, a spokesperson for Downing Street referred reporters to comments Burnham made in parliament when he vowed to "stick to the Good Friday Agreement 100 percent".

Conservative deputy leader Alex Burghart said Trump was "very wrong", adding Northern Ireland was "an integral part" of the UK.

The row could also complicate Washington's relations with Northern Irish parties. While the socialist republican party Sinn Féin has boycotted the annual St Patrick's Day visit to Washington over Trump's Middle East policy, leading unionist parties, the Democratic Unionist Party and Ulster Unionist Party, have continued to engage with the president.

In response to his comments, DUP leader Gavin Robinson said Northern Ireland's future would be decided by its people, not "commentary in London, Dublin or Washington".