Trump would 'love to see' reunified Ireland and Northern Ireland

US President Donald Trump has said a unified Ireland would be "fantastic" as he waded into a complex and politically charged subject during a weekend visit to a tournament at his Irish golf course.

Meeting Irish Prime Minister Micheal Martin in Dublin, the US president said he would love to see the reunification of the Republic of Ireland with the United Kingdom's Northern Ireland.

"I don't want to cause any problems, but I'd love to see it unified," Mr Trump told a reporter who sought his opinion on the issue.

"I think it would be a fantastic thing," he said, adding that the "the UK will have something to say about it, obviously".

Later on, at the next stop on his tour, Mr Trump said there was "no good answer" to the reunification question as he addressed business leaders gathered at the US ambassador's residence.

The visit by the leader angered some residents of Dublin who staged protests.

Police cordoned off Phoenix Park where Mr Trump visited the respective homes of Ireland's prime minister, president and ambassadors.

Many in the crowd waved Irish or Palestinian flags and chanted, "Donald Trump not welcome here" and "Irish government, shame on you".

Speaking to Irish national broadcaster RTE on Friday in Doonbeg, Mr Trump's son Eric defended the visit and said the golf course was the largest employer in the area.

"Go down to Morrissey's tavern in Doonbeg and hear from a real Irish person as to whether or not they like President Trump and the Trump family, go have them attest to what we've done for the country and what we've invested in the country and the love and respect that our family has always shown them," he said.

Mr Trump's visit is the latest example of blending his official duties and personal interests.

Competing visions of Northern Ireland, whether Irish or British, drove decades of violence in the six-county region that has a Protestant majority and has remained part of the UK.

Previous American presidents, including Democrat Joe Biden have avoided commenting directly on the subject.

Ireland became a self-governing Catholic-majority country a century ago.