Ukraine has appealed to citizens of the world to join in the ongoing fight against Russia.

President Volodymyr Zelensky, in a statement on Sunday, accused Russia of killing civilians and praised Ukrainians for having the courage to defend themselves.

“All citizens of the world, friends of Ukraine, peace and democracy,” Mr Zelensky said. “Anyone who wants to join the defense of Ukraine, Europe and the world can come and fight side by side with the Ukrainians against the Russian war criminals.”

The statement added that those who wish to join should contact the Defense Attache of the Embassy of Ukraine in their countries.

Ukraine, in the statement, noted military regulations that acknowledged the right of foreigners to join its Armed Forces for military service under Contract on a voluntary basis. 

“According to Regulation on Military Service in the Armed Forces of Ukraine by citizens of their countries and stateless persons approved by Decree of the President of Ukraine # 248 of June 10, 2016, foreigners have the right to join the Armed Forces of Ukraine for military service under Contract of a voluntary basis to be included in the Territorial Defense Forces of the Armed Forces of Ukraine,” the statement said. 

Meanwhile, the United Nations High Commission for Refugees says over 150,000 people have fled Ukraine since Russia’s assault began on Thursday. 

UN High Commissioner for Refugees, Filippo Grandin, said in a tweet on Saturday that half of all Ukrainian refugees had crossed into Poland, and many others have gone to Hungary, Moldova and Romania.

United Nations aid agencies had earlier warned that fuel, cash and medical supplies were dwindling in Ukraine, which could lead up to five million people fleeing the country.