A 48-hour ban on flights from Britain will start at midnight tonight, the Transport Minister has confirmed.
Eamon Ryan says ferry connections with Britain will be for cargo only.
Several other European countries - including the Netherlands, Italy and Belgium - have also banned flights from the UK amid concern over a new strain of coronavirus that has been detected in England.
Cabinet is expected to review the issue when it meets on Tuesday, and Minister Ryan says the ban may be extended.
Coalition leaders met this afternoon and agreed on the temporary ban - and now say nobody in Britain, regardless of nationality, should travel to Ireland.
They add the only exception is for essential supply chain workers.
Minister Ryan said: "In the circumstances it's appropriate for us to stop air traffic from Great Britain.
"We thought it was appropriate to put it in place for 48 hours, review how it's working, and whether further or [fewer] measures are needed."
Meanwhile, the Northern Ireland Executive will meet this evening to discuss their response the situation in England.
Elsewhere, the Labour party has now called for mandatory COVID-19 testing at ports.
The party's TD Duncan Smith urged the Government to bring forward the Cabinet meeting scheduled for Tuesday, and to 'ramp up' testing and tracing capacity over the coming days.
He said: “If this new strain is so widespread now in the UK then it is highly likely it could already have spread to Ireland but we don’t have testing at our frontiers to catch it.
“What this shows is the urgent need for mandatory COVID-19 testing at our airports and seaports for visitors arriving into Ireland over the coming days and weeks."