The European Central Bank has given eurozone banks until 2022 to limit their reliance on their London operations for booking trades and loans following Britain's exit from the European Union, the Financial Times wrote on Monday.

The ECB, as the eurozone's top banking watchdog, has long said banks will have to phase out the so-called "back-to-back" booking of EU trades in London. It has now set a three-year deadline to do so, the FT wrote, quoting a banker saying the ECB expected "a lot of" back-to-back booking to be phased out even sooner.

Reuters reported in July that banks had been told to agree to a two- to three-year window for moving staff and functions to the euro zone.

A spokeswoman for the ECB declined to comment.

Britain is formally due to leave the EU in March 2019.

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