More than 4.5 million people have fled Ukraine since the beginning of the invasion ordered by Russian President Vladimir Putin, according to figures updated this Sunday by the United Nations High Commissioner for Refugees (UNHCR).

According to Lusa, this Sunday's update counted 4,503,954 refugees, 62,291 more than Saturday's figure, in what is the largest movement of refugees in Europe since World War II.

About 90% of these people are women and children, as the Ukrainian authorities do not allow men of military age to leave.

According to the International Organization for Migration (IOM), some 210,000 people of other nationalities have also fled Ukrainian territory, with difficulties in returning to their home countries.

The United Nations estimates that there are still 7.1 million people displaced within Ukraine, a figure updated by the IOM on April 5.

A total of more than 11 million people - more than a quarter of Ukraine's population - were forced to flee because of the Russian invasion.

Most of the refugees leaving Ukraine are in Poland, which until Saturday received 2,593,902 people, although on Sunday the Polish border service's accounting reached 2.63 million.

There are at least 686,232 refugees in Romania, a large part of whom first passed through Moldova, a country that took in at least 410,882 refugees.

Already in Hungary there are 419,101 refugees, 314,485 in Slovakia, and at least 404,000 have gone to Russia, 113,000 of whom left from the pro-Russian separatist-controlled territories of Donetsk and Lugansk.