Outgoing US President Joe Biden has announced another tranche of security assistance for Ukraine worth some $2.5 billion, as he seeks to bolster Kiev's defences against the Russian invasion before leaving office in January.

President Joe Biden said Monday that the United States will send nearly $2.5 billion more in weapons to Ukraine as his administration works quickly to spend all the money it has available to help Kyiv fight off Russia before President-elect Donald Trump takes office.

The US on Monday announced almost $5.9 billion in military and economic aid for Ukraine, some of the final funds to be disbursed under President Joe Biden before an expected shift in support by incoming President-elect Donald Trump.

The United States "will continue to work relentlessly to strengthen Ukraine's position in this war over the remainder of my time in office," Biden said.

The Biden administration said Monday that it is sending nearly $6 billion in additional aid to Ukraine, likely the last tranche of funding before President Biden leaves office. The package includes nearly $2.