Ryanair chief executive Michael O’Leary has described the economic plan put forward by the UK Government as “nuts”.
Mr O’Leary said the mini-budget could potentially bankrupt the UK economy in the coming years.
Chancellor Kwasi Kwarteng last week announced plans to scrap the top rate of tax and cut the basic rate to 19p in the pound.
The announcement sent the the pound spiralling, with it eventually falling to an all-time low against the dollar.
Speaking in Dublin, Mr O’Leary said: “I think what they have done in the UK is nuts,” Mr O’Leary said.
“You can’t have an energy guarantee that runs for two years. It’s completely uncosted.
“I think they could bankrupt the UK economy in the next two years.
“We (Irish state) have been there with the bank guarantee back in 2007 and 2008, we can’t go back there again.”
The Irish deputy premier Leo Varadkar said he is not “unduly concerned” about the move.
“We are obviously paying attention to what happens next door. It is our nearest neighbour and one of biggest trading partners,” Mr Varadkar added.
“Just as the case with the United States or the Eurozone, if one of our trading partners goes into recession that has an impact on us.
“So we are looking closely at the situation in other countries, but I am not unduly concerned at this stage.”
On Tuesday, the Irish Government unveiled its 11 billion euro budget plan for next year.
The cost-of-living budget is designed to help householders pay their rising energy bills, and contained a number of welfare increases, tax cuts and business grants.
Mr O’Leary said the Irish Government pitched its budget “sensibly”.
“I wouldn’t personally agree with some of the spending. As a father of four children I don’t need an additional children’s allowance,” Mr O’Leary added.
“But I think the Government has pitched it sensibly.”