Warsaw, 12 June 2022 (dpa/MIA) - The number of Ukrainians who have left their country for Poland since Russia's invasion in February has crossed the 4-million mark, according to the Polish border patrol agency in a tweet on Sunday. The latest data shows 24,900 people arriving in Poland on Saturday, pushing the number above the new mark. However, it is impossible to say how many of those people have stayed in Poland and how many have travelled further on into other Western European countries. Polish President Mateusz Morawiecki recently said his country is hosting about 2 million Ukrainian refugees. Nor is the flow one-way. Polish authorities on Saturday also noted 28,000 people heading into Poland, many of them returning to areas that have been brought back under Ukrainian control after Russia's initial invasion. Ukraine had a population of more than 44 million before the invasion. Many of those fleeing headed to Poland, which shares a 500-kilometre-long border with Ukraine.