According to the banking ombudsman, 38 percent of its complaints came from abroad -- little change from 2010 (37 percent) -- but significantly higher than in 2009.
The total number of complaints was down five percent from 2010, to 1,889.
"Before the financial crisis, we received around 130 new cases per month, now it's up to 160," said ombudsman Hanspeter Häni.
Among its other tasks the ombudsman's office looks into claims from individuals who believe they have a right to funds locked in Swiss bank accounts which have not been accessed for 10 years or more.
In 2011, the ombudsman received 735 such claims, of which 457 accounts were uncovered and the contents of 38 accounts transferred.
Some 5.4 million francs ($5.7 million) were returned to individuals in total, along with the contents of six safety deposit boxes.
Nearly 29 percent of the successful claims came from Germany, followed by France (15.8 percent) and South America (10.5 percent).