British-based clearing houses should not be forced to move to the European Union after Brexit, a senior European Parliament lawmaker has said in a sign of a softening of Brussels’ hardline stance over the institutions' euro transactions.

The EU is mulling changes to its rules for clearing houses, the majority of which are in London, which could lead the biggest being forced to establish EU headquarters.

More than 90pc of the most important derivatives transactions in euros are cleared by British-based clearing houses, which, after Brexit, will be outside the EU.

On Wednesday, Danuta Hübner, the lead MEP on the draft law struck a more conciliatory tone, which reflects a growing recognition in Brussels that simply forcing clearing to move out of London would pose more problems than first thought.

The Bank of England and industry figures have warned that forced relocation would mean fragmenting markets in Europe, bumping up costs and potentially seeing the activity shift to New York.

As rapporteur on the legislation Mrs Hübner, a member of the largest and most influential political group in the European Parliament, will helm amendments to the draft law, which will ultimately have to be agreed with national governments.

Mrs Hübner’s European People’s Party said in a statement that it did not want to force clearing houses to relocate but did want EU regulators to have more power over non- EU clearing houses if they dealt in euros.