Banking giant HSBC said on Monday that it was being investigated along with other banks as part of a worldwide probe into the possible manipulation of foreign exchange trading.
It comes as the bank, the biggest in Europe, announced a 28-percent jump in quarterly net profit to $3.2 billion (2.37 billion euros).
The London-based bank said in its earnings statement that British regulator, the Financial Conduct Authority, "is conducting investigations alongside several other agencies in various countries into a number of firms, including HSBC, relating to trading on the foreign exchange market".
HSBC added that it was "cooperating with the investigations which are at an early stage".
HSBC joins British banks Barclays and Royal Bank of Scotland (RBS) in confirming that they are part of the investigations.
Deutsche Bank, Swiss lender UBS and US pair Citi and JPMorgan Chase have also come forward to say that they are co-operating with regulators over the affair.
According to sources, Barclays has suspended six traders while it investigates the possible manipulation of foreign exchange markets and RBS has suspended two.
The banking sector has already been shaken by a rigging scandal related to the Libor, a benchmark interest rate for lending between banks which also determines numerous financial and interest rate contracts around the world.
That scandal has already resulted in more than $3.5 billion in government settlements with financial institutions, as well as ongoing criminal prosecutions of several traders involved.