Kazakhstan's currency, the tenge, has plunged in value by over 20 percent against the dollar after the government decided to move to a free float.

The Kazakhstan Stock Exchange said the tenge was trading at over 250 to the dollar Thursday afternoon after closing at 197.05 the day before.

The collapse follows a fall in the price of oil, Kazakhstan's main export, and drops in the value of the currencies of the country's main trading partners, Russia and China.

Local media in Kazakhstan report that the fall in value of the tenge has triggered a rush to buy luxury imported goods ahead of expected price rises and that many currency exchanges had closed for the day.