WASHINGTON, Nov 18 (Reuters) - U.S. President Joe Biden pledged a $4 billion U.S. contribution to the World Bank's International Development Association fund for the world's poorest countries, a senior Biden administration official said on Monday.

Biden announced the three-year U.S. pledge during a closed session of the Group of 20 summit in Rio de Janeiro, the official told reporters, adding that the U.S. Treasury was leading negotiations at the World Bank for the IDA replenishment.

The new U.S. pledge is a record and substantially exceeds the $3.5 billion Washington committed in the previous IDA fund replenishment round in December 2021.

It is unclear if U.S. President-elect Donald Trump, who has proposed cutting foreign aid in the past, will honor Biden's pledge as he and billionaire Tesla and SpaceX CEO Elon Musk seek to slash U.S. spending through a new government efficiency panel. An appropriation by the U.S. Congress to fund the commitment would not likely take place until after Trump takes office in January.

A spokesperson for Trump's transition team did not respond to a request for comment on the matter.