Russia's central bank has announced a bailout of the Trust Bank, one of the country's mid-sized lenders, following the dramatic collapse of the Russian ruble.

The troubled bank has been placed under the central bank's supervision, and will also receive 30 billion rubles (£340m, $530m) in order to stave off bankruptcy.

The central bank did not say whether the lender's problems were directly related to the dramatic fall in the ruble, which has lost around 40% of its value since the summer.

The central bank's Deposit Insurance Agency is now supervising Trust's operations with immediate effect while a major bank was being found to provide additional investment, a statement said.

The collapse has largely been the result of falling oil prices, on which Russia depends for two thirds of its overall export revenues and half of its annual budget.

Trust Bank's products are advertised by the Hollywood actor Bruce Willis.