European lenders could be barred from accessing U.S. futures markets due to an American regulator's dissatisfaction over EU plans for foreign clearing house regulations post-Brexit, The Daily Telegraph reported.

At present most clearing activities in U.S. dollar and euro currencies take place in London, but European authorities want all euro activities done inside the EU once the U.K. leaves the bloc.

Christopher Giancarlo, head of the U.S. Commodity Futures Trading Commission, said that the EU's plan to revise the European Market Infrastructure Regulation was "wholly unacceptable," the newspaper said Oct. 17. The official said the amendment could result to "costly burdensome regulatory requirements" in the U.S.

If the plan is not changed, Giancarlo reportedly said he would have to consider measures such as blocking EU banks from using U.S. financial infrastructure. However, he said he was open to negotiations "to work out a sensible approach."