The European Commission has begun an anti-trust investigation into ties between Rabobank and Deutsche Bank after concluding they may have colluded to distort competition in bonds trading.

The commission said in a statement on Tuesday that it had ‘concerns’ that between 2005 and 2016 traders at the two banks had ‘exchanged commercially sensitive information and coordinated their pricing and trading strategies’.

‘These exchanges would have taken place mainly through emails and online chatroom communications,’ the commission said.

If proven, this would violate EU rules banning anti-competitive business practices such as collusion on prices and other trading conditions, the commission said.

The commission said it had been looking into a possible settlement but ended the talks because of a lack of progress.

In two previous bond-related cartel cases the commission has fined the banks concerned millions of euros. The fine can be up to 10% of annual turnover.

Rabobank told the Financieele Dagblad it is too early to comment on the case.