A refugee child is seen at Ritsona refugee camp in Ritsona, Greece, on June 20, 2021, World Refugee Day. Residents of Ritsona refugee camp, an hour's drive northwest of Athens, marked World Refugee Day on Sunday with a symbolic demonstration held around the site that hosts about 3,000 people.

Refugees take part in a demonstration to mark World Refugee Day at Ritsona refugee camp in Ritsona, Greece, on June 20, 2021. Residents of Ritsona refugee camp, an hour's drive northwest of Athens, marked World Refugee Day on Sunday with a symbolic demonstration held around the site that hosts about 3,000 people.

Palestinian refugee children play in Jabalia refugee camp in the northern Gaza Strip, on June 20, 2021, World Refugee Day. (Photos: Xinhua)

A Palestinian refugee girl is seen outside her house in Jabalia refugee camp in the northern Gaza Strip, on June 20, 2021, World Refugee Day.

A Palestinian refugee child has a popsicle in Jabalia refugee camp in the northern Gaza Strip, on June 20, 2021, World Refugee Day.

Palestinian refugee children are seen in Jabalia refugee camp in the northern Gaza Strip, on June 20, 2021, World Refugee Day.

A girl is seen at a school run by the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) at the Shati refugee camp in Gaza City, on June 20, 2021, World Refugee Day.

Children play at a school run by the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) at the Shati refugee camp in Gaza City, on June 20, 2021, World Refugee Day.