The franc has fallen steadily against the euro this week as traders eye inflation data and mull the possibility of the Swiss National Bank raising the 1.20 francs per euro floor it pledged to defend in early September to stave off recession.

Foreign reserves data released by the SNB on Thursday show the central bank has so far succeeded in defending the 1.20 level without its balance sheet ballooning, Credit Suisse analysts said in a note.

"The SNB figures revealed that Switzerland's foreign exchange reserves increased by a very manageable 29 billion Swiss francs," they said.

"This suggested that the SNB had encountered little resistance over the past month since it floored the franc to the euro at 1.2000."

The franc fell marginally against the euro compared to the New York close to trade at 1.2375 francs per euro at 0718 GMT.

The franc was 0.2 percent higher against the dollar at 0.9195 francs to the dollar, but remains more than 1 percent down on the week.