Increase of the rate of refinancing: Could the banks unilaterally change the rate on the previously issued loans?

Since the 16th of December 2014 the key rate of the Bank of Russia has been increased up to 17%. This is reported on the official site of the Bank of Russia. It is explained in the Bank of Russia that this decision occurs due to the necessity to restrict the essentially increased devaluation and inflation risks. The key rate is a rate on which the Bank of Russia provides loans to the commercial banks for one week as well as is ready to accept from banks money for deposit for the same period. It affects the amount of rates on the bank loans and the inflation rate.
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