MANILA—Russia's military has committed indiscriminate attacks on civilians and protected areas such as hospitals during its invasion of Ukraine, Amnesty International has said.

The global human rights watchdog said these were violations of international humanitarian law and could amount to war crimes.

Marie Struthers, Amnesty International's regional director for Eastern Europe and Central Asia, said 3 people, including a child, were killed when a nursery and kindergarten were hit with cluster munitions on Feb. 25 while civilians took shelter inside.

The strike violates the prohibition on indiscriminate attacks and damaged a school, a structure legally entitled to special protection, the group said in a statement.

Under the 2008 Convention on Cluster Munitions—a treaty backed by more than 100 states, but which Ukraine and Russia have not joined—the use, development, production, acquisition, stockpiling and transfer of cluster munitions is prohibited under all circumstances.

Struthers stressed that under international humanitarian law, educational facilities are entitled to heightened protections if they were not used for military purposes.

"All parties to armed conflict are supposed to take special care around schools. That's not the track record for Russia," she said in an interview with ANC's "Rundown" that aired Monday.

"We've been monitoring the Russian army's conduct in Syria, in Chechnya, and of course, during the 2008 war in Georgie and sadly in all of those conflicts, Russia's armed forces have shown blatant disregard for the protection of civilians and blatant disregard for their obligation to not target civilians at any cost," she added.

In its report, Amnesty International said it was the fourth attack in the Ukraine-Russia crisis, which has struck a school that the group had verified.

On Feb. 17, during increased shelling along the line of control, Russian-backed forces struck a kindergarten in the town of Stanytsia Luhanska, wounding 3 civilians.

On Feb. 25, a missile damaged School No. 48 in Mariupol, blowing in windows and pockmarking the walls with metal fragments, the group said.

On Feb. 26, an explosive weapon hit the second story of a kindergarten in Chernihiv, starting a fire that was likely detected by VIIRS environmental satellite sensors.

Amnesty International said while Russia and Ukraine are not parties to the International Criminal Court, Ukraine in 2015 accepted the court’s jurisdiction over alleged crimes committed on its territory from Feb. 20, 2014.

"I would say that given increasing unity in the entire international community and a round condemnation of Russia's actions, there's a good chance that cases will be able to be brought before the international court of justice as advocated by [Ukrainian] President [Volodymyr] Zelensky," she said.

Around 400,000 Ukrainians have crossed into the EU since the start of the offensive on Thursday, according to a tally by the Agence France-Presse. Half of them entered Poland, its government said.

Ukraine has reported 198 civilian deaths, including 3 children, since the invasion began and Russia acknowledged for the first time that a number of its forces had been killed or injured.

The UN has put the civilian toll at 64 while the European Union said more than 7 million people could be displaced by the conflict.

Russia has become an international pariah as its forces do battle on the streets of Ukraine's cities, facing a barrage of sanctions including a ban from Western airspace and key financial networks.

-With a report from Agence France-Presse