Swiss bank UBS has told employees that the majority of those affected by Brexit will move to Frankfurt from London, setting out what it called a decentralised approach to relocating staff.

The logo of Swiss bank UBS at its headquarters in London on May 5, 2017.

The moves are expected to affect fewer than 200 UBS staff, a source familiar with the plans told Reuters. UBS employs around 5,000 people in London.

Staff affected will be informed in the next few months and relocations will depend on where clients are based, according to a company memo seen by Reuters.

Separately, the Swiss bank said in its annual report on Friday that it will merge UBS Limited, its British entity, into UBS Europe SE, its German headquartered European bank, in the absence of a transition deal between Britain and the EU.

That would take place prior to Britain leaving the European Union on 29 March, 2019.

"After a thorough analysis, which included your feedback, we have opted for a more decentralized model and plan to leverage our existing UBS Europe SE and its extensive branch network," UBS's investment banking chief Andrea Orcel said in the memo.

The plans announced by UBS are the latest sign of how banks are starting to execute on Brexit contingency plans after British Prime Minister Theresa May ruled out retaining passporting rights for financial services.

The loss of these passporting rights - which currently enable finance firms to freely offer financial, advisory and trading services to corporate clients across all EU states via just one local license - is a major concern for banks.

Goldman Sachs said this week it was starting to transfer some senior bankers to Frankfurt in preparation for Britain's exit from the EU. Standard Chartered has started interviewing candidates for about 20 jobs it is moving to Frankfurt, its chief financial officer told Reuters.