Banks in the natural gas-rich Central Asian nation of Turkmenistan have halted hard currency sales as the economy shows signs of struggling amid falling global energy prices.

Employees at banks in the capital, Ashgabat, told customers Tuesday that the ban on the sale of U.S. dollars and other hard currencies would remain in place indefinitely.

Currencies in other ex-Soviet nations have been buffeted by a combination of plummeting prices for commodities and Russia's sagging economy.

Turkmenistan's currency, the manat, has officially held at around 3.50 against the dollar over the past year, although rumors of an imminent sharp devaluation have created strong demand for foreign currencies.

The nation is run by a strict authoritarian government, making any protests against currency restrictions unlikely.