The press conference, scheduled for 2:15 PM ET following the release of the FOMC statement at 12:30 PM, is the first of its kind by a Fed chief, though it is common practice for other central banks including the ECB.

FORBES: Markets Await Bernanke's Historic Moment

For the Conservatives, shadow foreign secretary William Hague said it was "astonishing" Mr Brown had taken so long to comment on the matter and that the PM was not prepared to address the question of whether Megrahi's release was justified.

BBC: PM 'repulsed' at bomber welcome