Swiss competition authorities said Monday they were investigating UBS, HSBC, Deutsche Bank and four other banks on suspicion of price fixing in the precious metals market.

The Swiss Competition Commission (COMCO) "has today opened an investigation against two Swiss banks, UBS and Julius Baer, as well as against the foreign financial institutions Deutsche Bank, HSBC, Barclays, Morgan Stanley and Mitsui," it said in a statement.

It said it had indications that the banks had "possibly concluded illegal (price-fixing) deals ... within the precious metals market."