The head of the top derivatives regulator in the US has waded into the debate around euro clearing in London, warning the European Union to tread carefully with decisions about its future oversight of clearing houses.

The European Commission is in the process of weighing up options for strengthening the regulation of clearing houses that play a systemic role in the region. The EU’s executive arm is deciding its policy as the UK, where 75% of euro-denominated interest-rate derivatives are cleared, prepares to leave the bloc.