Ireland on Thursday announced the closure of all schools and colleges, and recommended the cancellation of mass gatherings as part of measures to combat the spread of the coronavirus.

Prime Minister Leo Varadkar said "schools, colleges and childcare facilities will close from tomorrow (Friday)", as would state-run cultural institutions.

Indoor events of more than 100 people and those outdoor involving over 500 "should be cancelled", Varadkar said in a statement in Washington, where he was on an official visit.

Ireland has 43 confirmed cases of the disease and on Wednesday announced the country's first death. Varadkar said more cases and deaths were expected as the world moved into "uncharted territory".

The premier said the new measures were part of the government's "duty to protect" the public and the restrictions would be in place until March 29.

He said people could still go to work, as public transport was not affected, but recommended home-working, staggered working and break times wherever possible, to minimise contact.

The new guidance follows a meeting between the prime minister and the government's National Public Health Emergency Team on Wednesday night.

In Dublin, foreign minister Simon Coveney told a news conference: "This is a phase that we have been planning for some time."

He called them "the right measures, at the right time" and were based on best public health advice. Varadkar travelled to Washington for St Patrick's Day celebrations on March 17 for Ireland's patron saint.

The annual parades in Ireland, which attract hundreds of thousands of people, have been cancelled because of fears about the spread of COVID-19. Similar parades in Boston and New York have also been cancelled.