Ireland’s prime minister has denounced anti-immigration comments made by Conor McGregor as the MMA fighter visited the White House before a Saint Patrick’s Day meeting with Donald Trump.

McGregor said “Ireland is on the cusp of losing its Irishness” and that an “illegal immigration racket” was “running ravage on the country”.

Last week, Donald Trump singled out “Conor” – who last year was found liable for sexual assault after a civil trial – as one of his favourite Irish people.

Dressed in a green business suit to mark Ireland’s national day, McGregor was at the White House at Trump’s invitation and participated in an impromptu Q&A session with reporters. “There are rural towns in Ireland that have been overrun in one swoop,” he said, speaking in the White House briefing room alongside the president’s press secretary, Karoline Leavitt.

The 36-year-old former Ultimate Fighting Championship (UFC) champion said he was “here to raise the issue and highlight it” and that he would be listening to Trump on immigration – one of the president’s main areas of focus as he seeks to ramp up deportations of people in the US without proper documentation.

The apparently off-the-cuff comments were immediately condemned by Micheál Martin, the taoiseach. “Conor McGregor’s remarks are wrong, and do not reflect the spirit of St. Patrick’s Day, or the views of the people of Ireland,” the Irish prime minister said on X. “St Patrick’s Day around the world is a day rooted in community, humanity, friendship and fellowship.”

McGregor was among those at an official pre-inauguration party in Washington in January. He has been one of the biggest stars of the UFC, which was founded by the Trump ally Dana White.

In November McGregor was ordered by an Irish civil court to pay nearly €250,000 (£210,000) in damages to a woman who said he “brutally raped and battered” her in a hotel in Dublin in 2018. McGregor claimed they had consensual sex and is appealing against the verdict with a hearing in Dublin’s high court due later this week.

The fighter has said he is considering running for president in Ireland later this year, a prospect some thought would be ruled out after the civil trial verdict.

He has been supported by figures including the self-styled misogynist influencer Andrew Tate and anti-immigration campaigners in Ireland whose reach has been turbocharged by Elon Musk retweets.

Immigration is a hot topic in Ireland with many arrivals coming from the UK on ferries or via Northern Ireland. The justice minister, Jim O’Callaghan, has promised to clamp down on those who are not entitled to international protection. Last month he said more than 80% of applications for asylum in January were rejected in the first instance.