Jolie met Ukrainian patients at Bambino Gesù children's hospital.

Hollywood star and UNHCR special envoy Angelina Jolie on Wednesday made a surprise visit to young Ukrainian war refugees being treated at the Bambino Gesù paediatric hospital in Rome.

"I'm praying for the end of the war" - said the Oscar-winning American actress - "This is the the only way to stop the suffering and the fleeing from the areas of conflict."

"It is horrible to see children paying the price, in lives lost, health damaged and trauma," she said, Italian newspaper Corriere della Sera reported.

#Ucraina, visita a sorpresa di Angelina Jolie ai piccoli pazienti ucraini dell'ospedale Bambino Gesù di Roma. L’attrice statunitense nella capitale per girare un film@TgrRaiLazio @bambinogesu#IoSeguoTgr pic.twitter.com/blV2ua2u93— Tgr Rai (@TgrRai) March 31, 2022

Jolie's visit came the same day that the UNHCR announced that four million Ukrainians had fled the country after Russia's invasion more than a month ago.

• Pope pays surprise visit to Ukrainian refugee children in Rome hospital

The Vatican-run hospital is currently treating 31 Ukrainian children, some of whom were injured in the war, while others are receiving treatment for serious illnesses after the disruption of their medical care in Ukraine.