WASHINGTON (Reuters) - The United States supports the establishment of a special tribunal on the crime of "aggression" against Ukraine, a top envoy at the State Department and a spokesperson said, laying out for the first time how Washington would back Ukraine's accountability push over Russian invasion.

"We believe that this Special Tribunal should be rooted in Ukraine’s domestic judicial system, as this will provide the clearest path to establishing a new Tribunal and maximize our chances of achieving meaningful accountability," a State Department spokesperson said.

Beth Van Schaak, State Department's Ambassador at the Office of Global Criminal Justice also announced late on Monday Washington's support for such a court, saying that this model has been chosen following an analysis of several others.

"This kind of model—an internationalized national court—will facilitate broader cross-regional international support and demonstrate Ukraine’s leadership in ensuring accountability for the crime of aggression," she said in a speech at the Catholic University of America.

Ukraine, the European Union and the Netherlands have publicly backed the idea of a special tribunal. Russia, which calls its actions in Ukraine a "special military operation," has denied accusations of war crimes including deliberate targeting of Ukrainian civilians, thousands of whom have been killed.

The International Criminal Court (ICC) issued an arrest warrant earlier this month accusing Russian President Vladimir Putin of the war crime of illegally deporting hundreds of children from Ukraine. It said there are reasonable grounds to believe that Putin bears individual criminal responsibility.

Van Schaak said the court might also be located elsewhere in Europe, at least at first, "to reinforce Ukraine’s desired European orientation."

(Reporting by Humeyra Pamuk; Editing by Marguerita Choy)