Banks are in a quandary whether to start moving their operations out of the UK as the formal process of Brexit nears, according to a British newspaper.

Most international banks had warned before the June 23 referendum that they will have to move their operations and workforce out of the UK if the country decides to leave the European Union (EU).

According to the Guardian, UK PM Theresa May is being asked by local financial authorities to reach a deal to ensure smooth transition of businesses before she triggers the formal process of exiting the EU.

Britons voted by 52 to 48 percent last June to leave the EU and the tone of the public debate about what Brexit should look like has remained acrimonious.

Theresa May has pledged to trigger Article 50 of the EU’s Lisbon Treaty, the step that will launch negotiations on the terms of Britain’s exit, by the end of March.

The Brexit process will take years and May has given few details about what deal she will be seeking from the remaining 27 EU members.