Russia investigates adopted boy's death in US

* Three-year-old dies in Texas

* Case could reignite dispute with Washington

* Russia has banned adoptions by U.S. parents

By Sonia Elks

MOSCOW, Feb 19 (Reuters) - Russian investigators have opened an inquiry into the death of a three-year-old boy in the United States, in a case that could aggravate a row with Washington over adoptions in Russia.

Russian officials say they are concerned that Maxim Shatto, whose Russian name is Maxim Kuzmin, may have been beaten badly before his death on Jan. 21 in his adopted home of Texas.

Moscow seized on the case as justifying a new law banning adoptions of Russian children by Americans - a measure that has escalated a tit-for-tat row with Washington over trade and human rights.

Relations between the two Cold War-era superpowers have taken a turn for the worse since Vladimir Putin's return to the Kremlin last May put an end to the 'reset' in ties launched after President Barack Obama was first elected in 2008.

"I would like to draw your attention to yet another case of inhumane treatment of a Russian child adopted by American parents," Konstantin Dolgov, the Russian Foreign Ministry's human rights representative, said in a statement.

U.S. authorities say the circumstances around Kuzmin's death are still under investigation, and that they cannot comment.

Russia's Investigative Committee, a government body in charge of criminal investigations, has now opened 10 investigations into actions suspected of "threatening the lives and health" of Russian-born children in the United States.

"The Investigative Committee will take all necessary measures to ensure that the killer of a Russian child suffers the most severe punishment," it said in a statement.

The U.S. has previously refused to hand over data to Russian investigators, and the two countries do not have bilateral extradition agreements, meaning the Russian probe is likely to be purely symbolic.

Russia banned U.S. adoptions as of Jan. 1 in retaliation for the U.S. Magnitsky Act, drawn up over concern about the death in a Russian prison of anti-corruption lawyer Sergei Magnitsky in 2009. The act will deny visas to Russians accused of human rights abuses and freeze their assets in the United States.

The head of the Russian lower house of parliament's committee for family, women and children called for all children who had already been adopted in America to be returned to Russia.

Shatto was adopted with his younger brother Kirill from an orphanage in Pskov in northwest Russia.

American families adopt more Russian children than those of any other country, with more than 60,000 cases since the 1991 collapse of the Soviet Union, including 962 in 2011.

Moscow has said its ban was justified by the deaths of 19 Russian-born children adopted by U.S. parents in the past decade, and what they perceive as lenient treatment of the parents.

The U.S. embassy in Moscow did not immediately comment. (Reporting By Sonia Elks; Editing by Jason Webb)