The European Union's markets watchdog asked its British counterpart yesterday to ensure that ICE Futures Europe and the London Metal Exchange (LME) fully comply with the bloc's market transparency rules for commodity derivatives.
The clash comes less than a week after Britain left the EU, though it has undertaken to apply all EU financial rules during the transition period that began after Brexit last Friday and lasts until the end of December.
It is also a sensitive time for the UK as it embarks on talks with the bloc over a future trade deal.
Britain is seeking future EU financial market access based on the bloc's system of equivalence which requires a non-EU country's rules to be similar to those in the bloc.
The European Securities and Markets Authority (ESMA) said it "encourages" Britain's Financial Conduct Authority to "employ timely" measures (FCA) to ensure compliance with transparency obligations at ICE Futures Europe and the LME.
The FCA said it does not share ESMA's view that it has taken no appropriate action with the exchanges.
"We want to ensure that implementation happens in such a way so as not to disrupt trading, which would affect end-users of these markets. We expect this work to be completed by the middle of the year," the FCA said.
The LME said it had prioritised market consultation.
"This active engagement with members and clients has allowed the scoping of a solution which reflects the specificities of our market," LME said. "We look forward to working closely with all stakeholders to implement the solution by mid-2020."
ICE Futures Europe declined to comment.