The central bank of Switzerland said Thursday it wiould introduce a negative interest rate to fend off a further strengthening of the Swiss franc. From January, banks will be charged 0.25 per cent interest on their checking accounts at the Swiss National Bank (SNB). According to dpa, the decision followed the European Central Bank's setting of a negative interest rate for such accounts in June. Switzerland's negative rates will make it less attractive to invest in the Swiss currency, said SNB, which has been defending a minimum rate of 1.20 francs (1.25 dollars) per euro.