For all the transparency forced on the Federal Reserve by Congress and the courts, one of the central bank’s emergency-lending programs remains so secretive that names of borrowers may be hidden from the Fed itself, Bloomberg reported.

As part of a currency-swap plan active from 2007 to 2010 and revived to fight the European debt crisis, the Fed lends dollars to other central banks, which auction them to local commercial banks. Lending peaked at $586 billion in December 2008.

Though the transactions with other central banks are all disclosed, the Fed doesn’t track where the dollars ultimately end up, and European officials don’t share borrowers’ identities outside the continent, Bloomberg said.

The lack of openness may leave the U.S. government and public in the dark on the beneficiaries and potential risks from one of the Fed’s largest crisis-loan programs. The European Central Bank’s three-month dollar lending through the swap lines surged last week to $50.7 billion from $400 million after the Nov. 30 announcement that the Fed, in concert with the European Central Bank and four other central banks, lowered the interest rate by a half percentage point.

The secrecy surrounding foreign central banks’ emergency lending contrasts with unprecedented transparency at the Fed, which was compelled by the 2010 Dodd-Frank Wall Street Reform and Consumer Protection Act and court-upheld Freedom of Information Act requests to release details on more than a dozen programs used to combat the U.S. financial crisis from 2007 through 2010.

Fed Chairman Ben Bernanke this year began holding regular press conferences and has said he is considering ways to make the Fed’s objectives more clear to the public.

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