The Department of Foreign Affairs has advised Irish citizens in Ukraine to leave immediately.
The updated advice comes as fears grow that Russian president Vladimir Putin could order an invasion in the coming days.
Ireland will keep its embassy in Kyiv open with a small number of essential staff remaining.
A department statement said: “Following intensive consultations overnight and this morning with EU partners in Kyiv and Brussels, and with other partners, the Department of Foreign Affairs has upgraded travel advice for Ukraine.
“We advise against all travel to Ukraine and ask citizens currently in Ukraine to leave immediately by commercial means.
“The updated travel advice is at dfa.ie/travel.
“Any Irish citizens requiring emergency consular assistance should contact the Department of Foreign Affairs at +353 1 4082000.”
The statement continued: “In common with the Embassies of partner states, the Embassy of Ireland in Kyiv will remain open, with a small number of essential staff remaining.
“That situation will be kept under review.
“The department has been in direct contact with all of those scheduled to travel to Ukraine for surrogacy purposes in recent days.
“The department will continue to provide support to each of these individuals and families with advice relevant to their particular situation.
“We remain in ongoing contact at senior level with EU partners, as well as the UK and the US, regarding the wider political and security situation in and around Ukraine.”
The updated advice came as US secretary of state Antony Blinken warned further aggression from Moscow would be met with a “resolute, massive and united transatlantic response”, during a call with Russian foreign minister Sergei Lavrov.
US President Joe Biden and Mr Putin are due to discuss the crisis by phone on Saturday, as the Pentagon orders an extra 3,000 troops to Poland to support allies.
UK defence Secretary Ben Wallace said an invasion could come “at any time”, while US national security adviser Jake Sullivan said an attack before the end of the Winter Olympics on February 20th is a “credible prospect”.
Western leaders have threatened Moscow with a damaging package of sanctions in the event of a further incursion into Ukrainian soil.
