CAIRO, Dec 11 (Reuters) - The Egyptian pound held steady at a central bank dollar sale on Thursday, but weakened slightly on the unofficial market.

The bank offered $40 million and said it had sold $38.8 million at a cut-off price of 7.1401 pounds a dollar, unchanged from its last sale on Wednesday.

The rates at which banks are allowed to trade dollars are determined by the results of central bank sales, giving the bank effective control over official exchange rates.

In the unofficial market, the pound was trading at about 7.74 to the dollar on Thursday, slightly weaker than Wednesday's rate of about 7.73 to the dollar, one trader said.

(Reporting Lin Noueihed Editing by Jeremy Gaunt)