As thousands of refugees wait long hours to cross the Greece-Macedonia border to head to more prosperous northern European countries, some respite is on offer for the youngest.

Charities have set up a children's play center, which opened about 10 days ago and is operational 24 hours a day, in the Idomeni camp, where children can watch cartoons or draw to pass the time while their parents wait for their family's turn to cross the border.

"We try to occupy the children, care for infants and also identify unaccompanied minors so efforts can begin to reunite them with their families," said Alexis Vrahnos, local coordinator of the Arsis charity that set up the play center in cooperation with Save the Children and Terre Des Hommes.

The play center is staffed round the clock by a psychologist, a teacher, two interpreters and a nurse.

Sitting at one table is 5-year-old Alman from Kobani, Syria, along with his two brothers. He proudly holds up the picture he's been drawing.

"It's a child walking on water," he tells a visiting reporter.

His father Mahmoud says the family traveled to the Greek island of Lesbos from the nearby Turkish coast — a short but perilous journey that has cost many lives as overcrowded dinghies or wooden boats capsize or sink.

"We had a difficult journey in the sea until we reached Mytilene," he says, referring to the island's capital. "The children were all wearing life jackets, but what they lived through was terrifying. Thankfully they will quickly forget it."

He didn't want to give a surname for fear of persecution of relatives back home.

Two sisters from the Syrian city of Hama — 4-year-old Sofia and her 3-year-old sister Lilas — as well as their three cousins, sit at the next table. Sofia draws a picture of flowers.

"When she sees many people, she gets very scared," said her father Mohamed Kheer. "The boys usually draw guns," he says of his three nephews. "The girls draw houses and flowers."