Russia's commissioner for children's rights said Monday that a Russian child died at the hands of his adoptive mother in the United States.

"Maxim, 3 years old, was beaten by his adoptive mother who, for a long time, gave him strong psychotropic medications," wrote Pavel Astakhov on Twitter.

The murder was committed in late January but there was no reaction from the U.S. State Department, the commissioner said.

The Russian Embassy in Washington learned of the matter through its own sources without being advised of it by U.S. diplomats, Astakhov added.

"Once again, the State Department, in contrast to the local authorities, did not help our consular representatives at all to clarify the causes of a new death of a Russian child in the U.S.," Konstantin Dolgov, head of the human rights division at Russia's foreign ministry, told the Interfax news agency.

Russia last December approved a widely criticized law prohibiting the adoption of Russian children by U.S. families.

The prohibition came in response to a U.S. measure imposing sanctions - including denial of visas and the freezing of assets - on Russian officials allegedly implicated in the 2009 death in prison of Russian attorney Sergei Magnitski.

Moscow justified its decision by pointing to several cases where the rights of children adopted in the United States were violated. EFE