Poland’s border guard counted more people leaving Polish territory for Ukraine on Sunday than entering Poland from its war-torn neighbour.
The border guard said on Twitter on Monday that some 19,300 people had left Poland for Ukraine in 24 hours. Some 17,300 people entered Poland from Ukraine in the same period, 10% fewer than the previous day.
According to UN figures, more than 2.81 million people have fled Ukraine for neighbouring Poland since the beginning of the Russian invasion on February 24.
Ukrainian returnees mostly travel to areas that the Ukrainian army has recaptured as Russian forces have retreated east.
There is no official information on how many refugees have stayed in Poland and how many have travelled on to other EU states.
Ukraine had more than 44 million inhabitants before the Russian invasion. Poland and Ukraine are connected by a border more than 500 kilometres long.