The central bank said it was determined to defend a cap of 1.20 per euro it imposed in September and was ready to buy foreign currency in “unlimited quantities”.
“Even at the current rate, the Swiss franc is still high. Another appreciation would have a serious impact on both prices and the economy in Switzerland,” SNB chairman Thomas Jordan said.
“The SNB will not tolerate this. If necessary it stands ready to take further measures at any time.”
The SNB had to expand its forex reserves by nearly a third to make the cap stick last month, as fears rose of a Greek exit from the euro.