By Mike Stone

WASHINGTON The Pentagon overvalued U.S. equipment it sent to Ukraine by around $3 billion, a Senate aide and a defense official said on Thursday, an error that opens up the possibility of more weapons being sent to Kyiv for its defense against Russian forces.

The error was the result assigning a higher than warranted value on weaponry that was taken from U.S. stocks and then shipped to Ukraine, two senior defense officials said on Thursday.

"We've discovered inconsistencies in how we value the equipment that we've given" to Ukraine one of the senior defense officials told Reuters. The officials and the Senate aide spoke on the condition of anonymity. Congress is being notified of the accounting adjustment on Thursday, the sources said.

The defense official said it is possible the amount of overvalued weaponry could grow as the Pentagon examines the situation more thoroughly, increasing the $3 billion.

(Reporting by Mike Stone in Washington; Editing by Anna Driver)