No evidence so far to corroborate Russia allegations over Crimea - U.S.

U.S. ambassador to Ukraine Geoffrey Pyatt is seen before U.S. Assistant Secretary of State Victoria Nuland's news conference at the U.S. embassy in Kiev February 7, 2014. REUTERS/Gleb Garanich

KIEV (Reuters) - The United States has seen nothing so far that corroborates Russian allegations of a Ukrainian incursion into Crimea, the U.S. ambassador to Ukraine, Geoffrey Pyatt, said on Thursday.

Pyatt also said U.S. sanctions in relation to Russia's annexation of Crimea would remain in place until the territory was returned to Ukraine.