President Joe Biden's administration is readying about $800 million of additional US military aid to Ukraine and could announce it as soon as Friday, three sources familiar with the matter said on Thursday, Reuters reported.

Biden would authorize the assistance using his Presidential Drawdown Authority, which allows the president to authorize the transfer of excess weapons from US stocks, the sources said.

The sources, speaking on condition of anonymity, said that an announcement could slip into next week, cautioning that weapons packages can change in value before they are announced.

Washington has sent billions of dollars in military assistance to the Kyiv government ever since the beginning of the war.