The central bank set a cut-off price at the currency sale of 6.6025 pounds to the dollar, and the pound weakened further still to 6.6354 on the interbank market.

The central bank limits trades there to a 0.5 percent band above or below the weighted average of bids at the most recent currency auction.

Egypt's foreign reserves have tumbled during two years of domestic turmoil.

They stood at $36 billion before the uprising that toppled Hosni Mubarak and have now fallen to $15 billion, covering roughly three months of imports.

The central bank has said reserves are now at a critical level, though they have held steady for months with the help of billions of dollars of support from donors, particularly Gulf states.

Qatar has given or lent Egypt $5 billion in budget and other support.

In an initiative made public this week, the central bank said it was allowing lenders to temporarily refinance import operations for their clients, based on the banks' evaluation of the clients' creditworthiness.

The move is seen helping keep essential imports flowing into Egypt.

Investment bank Beltone said previous rules allowed such financing only to borrowers who could show they had the foreign currency resources to repay them at a later date.

"We expect that the temporary facilities in FX will only be provided to particular clients who are importing necessary items that go into the local production of other goods," Beltone said.

At Tuesday's auction, the bank offered $75 million and said it had accepted bids worth $73 million.