Foreign central banks' overall holdings of marketable securities at the Federal Reserve fell in the latest week, data from the U.S. central bank showed on Thursday.

The Fed said its holdings of U.S. Treasury securities kept for overseas central banks fell by $5.68 billion in the week ended December 8, to stand at $3.339 trillion.

The breakdown of custody holdings showed overseas central banks' holdings of Treasury debt fell by $2.87 billion to stand at $2.608 trillion.

Foreign institutions' holdings of securities issued or guaranteed by the biggest U.S. mortgage financing agencies, including Fannie Mae and Freddie Mac , fell by $2.81 billion to stand at $730.99 billion.

Overseas central banks, particularly those in Asia, have been huge buyers of U.S. debt in recent years and own more than a quarter of marketable Treasuries. China and Japan are the biggest two foreign holders of Treasuries.

The full Fed report can be found on: