At least 1,035 civilians have been killed and 1,650 wounded since Russia launched a war on Ukraine, the UN said Thursday. 

The number of fleeing Ukrainians exceeds 3.6 million.

The Office of the UN High Commissioner for Human Rights (OHCHR) said 48 children were among the dead in Ukraine but it referenced a report by the country’s Prosecutor General's Office that said 128 children had been killed and at least 172 injured.

Most of the civilian casualties recorded were caused by explosive weapons with a wide impact area. Others by shelling from heavy artillery and multiple-launch rocket systems and missile and airstrikes.

"(The) OHCHR believes that the actual figures are considerably higher, as the receipt of information from some locations where intense hostilities have been going on," it said.

The UN refugee agency said the number fleeing since the Russian military operation began Feb. 24 is 3,674,952, of which, more than 2.17 million have gone to neighboring Poland, a former Soviet bloc country.

Almost 564,000 have fled to Romania, more than 374,000 to Moldova, which was once part of the Soviet Union, over 330,000 to Hungary and the number in Slovakia exceeds 260,000.

Russia has also received more than 271,000 refugees.

The United Nations Children Fund (UNICEF) said earlier that one month of war has led to the displacement of 4.3 million children -- more than half of the estimated 7.5 million children in Ukraine.

Among the displaced children are more than 1.8 million who have crossed into neighboring countries as refugees and 2.5 million who are internally displaced inside Ukraine, it said.

"The war has caused one of the fastest large-scale displacements of children since World War II," said UNICEF Executive Director Catherine Russell.​​​​​​​​​​​​​​/aa