The United Nations sounded a dire warning on Friday, saying Russia's invasion of Ukraine could trigger a wave a refugees in neighbouring countries and that thousands had already made the journey.
The UN Refugee Agency in Geneva said that if the war continues to escalate, then it expects up to 4 million people to seek refuge outside Ukraine.
Thousands have already streamed across the border into EU countries Poland and Slovakia, as well as Russia and Moldova, it said.
The UN children's agency UNICEF said it was setting up shelters for women and children along escape routes and bolstering its presence in the region.
Slovakia said Thursday evening that it was already experiencing a rush on its border.
A queue formed at the Slovakia-Ukraine border crossing of Vysne Nemecke with wait times up to eight hours, the Slovak customs administration said.
The Slovak health authorities announced that war refugees were exempt from all coronavirus-related entry restrictions that apply to other entrants.
Poland recently said it planned to erect emergency shelters.
Hungary said this week it was sending additional troops to the border to manage an anticipated influx, including by providing humanitarian aid.
EU interior ministers were due to hold an urgent meeting on Saturday to discuss the potential for a large-scale wave of refugees into the bloc.
French Interior Minister Gérald Darmanin announced the meeting on Twitter but did not give any further details, such as the time and place.
