Swiss officials on Thursday backed new banking laws to prevent the failure of one or both of Switzerland's major banks from imperiling the rest of the banking system, but stopped short of calling for UBS or Credit Suisse Group to be split up.

"Our expert commission concludes that based on our four criteria, the two major banks can clearly be defined as 'too big to fail' in their current size and structure," Swiss National Bank director Thomas Jordan said at a media conference.