More than 4.5 million Ukrainian refugees have fled their country since the Russian invasion on February 24, according to the United Nations refugee agency. The UNHCR said there were 4,503,954 Ukrainian refugees on Sunday. That was 62,291 more than the previous day. Europe has not seen such a flood of refugees since World War II. Ninety percent of those who have fled Ukraine are women and children, as the Ukrainian authorities do not allow men of military age to leave. According to the UN’s International Organization for Migration (IOM), around 210,000 non-Ukrainians have also fled the country, sometimes encountering difficulties returning to their home countries. A further 7.1 million people have been displaced within the country, according to figures published by the IOM on April 5. That means more than a quarter of the population have been forced to flee their homes, seeking refuge either abroad or elsewhere in Ukraine. Before the conflict, Ukraine was home to more than 37 million people in territory controlled by Kyiv — which does not include Crimea, annexed by Russia in 2014, or areas in the east under the control of pro-Russian separatists. Poland hosts by far the largest number of refugees from Ukraine. Since the start of the war, 2,593,902 had crossed into Poland as of Saturday, the UNHCR said. For its part, the Polish border police said on Sunday it had recorded 2,630,000 arrivals. Many refugees travel on to other European countries. Of those who remain in Poland, 700,000 have already been granted a national identification number, the UNHCR said. The number is widely used in dealings with Polish public institutions and health services, to obtain a telephone number and access to certain banking services. Polish border police estimate that more than 500,000 people have returned to Ukraine since the conflict began. Poland had around 1.5 million Ukrainian immigrant workers before the war. The UNHCR said 686,232 people had travelled to Romania as of Saturday, most of whom arrived via Moldova and then continued on to other countries. After a visit to Romania this week, Raouf Mazou, the UNHCR’s assistant high commissioner for operations, hailed the government’s “rapid action” to afford Ukrainians temporary protection and thus “access to rights and services”. A total of 410,882 people have entered Moldova, the UNHCR said. The country of just 2.6 million, one of the poorest in Europe, is the closest to the Ukrainian port of Odessa. The European Commission is encouraging Ukrainian refugees to continue their journey to settle in a European Union country more able to bear the financial burden. As of Saturday, Hungary had taken in 419,101 people from Ukraine and Slovakia 314,485, the UNHCR said. A total of 404,418 people had arrived in Russia by Saturday. Between February 21 and 23 alone, 113,000 people crossed into Russia from the separatist regions of Donetsk and Lugansk in eastern Ukraine, the UNHCR said. As of Thursday, 19,096 were in Belarus. For the countries bordering Ukraine that are part of the Schengen zone — Hungary, Poland and Slovakia — the UNHCR figures are for people who have entered the country. It believes a large number have continued their journey on to other countries. The data does not include people from countries neighbouring Ukraine who have left to return home.