Officials in Washington opened new fronts in a probe of bank dealings in aluminium, oil and other raw materials, signalling intensifying scrutiny of possible conflicts of interest across the financial markets.

The Senate Permanent Subcommittee on Investigations has sought information in recent months from JP Morgan, Goldman Sachs Group and Morgan Stanley, people familiar with the matter said. The panel, led by Senator Carl Levin, is known for the 2010 hearings it held in a probe of Wall Street's role in the housing bust. A spokeswoman for the senator declined to comment.