The Swiss competition authority Comco said Friday that it is investigating UBS, Credit Suisse and 10 other financial institutions, broadening the scope of a global probe into allegations that banks colluded to manipulate market interest rates in London and Tokyo.

The new Swiss probe involves the London interbank offered rate, or Libor, a short-term interest rate between banks, and the Tokyo interbank offered rate, or Tibor. The rates are set by averaging quotes submitted by major banks and have an impact on fundraising costs for borrowers.