The Egyptian pound weakened further at a central bank dollar sale, moving towards black market rates, which stayed unchanged on Wednesday, the third day of Egypt's presidential elections.

Former army chief Abdel Fattah El-Sisi is expected to win the election.

Dollar shortages have fuelled a thriving black market in Egypt. Political turmoil following the 2011 uprising against Hosni Mubarak has unnerved foreign investors and tourists, who are traditionally major sources of foreign currency.

The central bank said it sold $37.6 million at a cut-off price of 7.1403 pounds, weaker than the 7.1352 pounds at its last sale on Monday. It had offered $40 million.

Forex traders and economists have described the central bank's decision to allow the pound to gradually weaken as a managed depreciation. The central bank has not given an explanation for allowing the currency to weaken in recent weeks.

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

One black market trader put Wednesday's rates at 7.45/48 pounds to the dollar, unchanged from Monday's and Tuesday's rates.

"There is not a lot of demand," he said referring to the weekend on Friday and Saturday and the exceptional public holiday the government had announced for Tuesday to boost voter turnout. "Maybe after the elections the pound will weaken again in the black market."

A weaker currency could help the country's economy, currently growing around 2 percent, by making Egyptian exports more competitive, economists have said.