A Japanese bank and and a Hong Kong-listed financial giant are among seven banks being investigated by Swiss authorities for alleged fiddling of precious metals markets.

Swiss authorities are probing a number of banks around allegations of price fixing in the market for precious metals such as gold.

The Swiss Competition Commission "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 emailed to this publication.

The Commission said it had indications that the banks had "possibly concluded illegal competition defying deals" in the trade of precious metals like gold, silver and platinum.

The investigation comes after a raft of banks had been already been punished for manipulating foreign exchange and interest rate benchmarks such as LIBOR. The scandals have fuelled public anger and driven calls for tighter regulation.