Egypt's central bank says it has weakened the value of the Egyptian pound against the dollar, its second devaluation this week.

The bank said in a statement that it weakened the pound at an auction on Sunday, dropping the value from 7.83 to 7.93 pounds per dollar.

The central bank has also allowed commercial banks a wider margin for selling and buying dollars since January, at 0.10 pounds above or below the official rate.

The central bank effectively controls the value of the domestic currency in regular foreign currency auctions.

The new rate could help boost much-needed foreign investment. Investors and economists see the currency as overvalued. Meanwhile, Egypt's foreign currency reserves continue to drop. The bank reported that reserves fell 9.7 percent in September to $16.3 billion.