Barclays has settled on Dublin for its main hub inside the European Union after Brexit and is planning to add about 150 staff there if UK-based finance companies lose easy access to the trading bloc, according to people with knowledge of the decision.

Bloomberg is reporting that the bank started scouting the city for office space this month and has been in contact with regulators here about expanding its operations, said the people, who asked not to be identified because the plans are not public.

Barclays is moving ahead with contingency plans so it can continue serving EU clients if UK Prime Minister Theresa May fails to strike a transitional or permanent deal preserving London’s access within the two-year renegotiation period.

"We have made clear repeatedly that we will plan for a range of Brexit contingencies, including building greater capacity into our existing operations in Dublin," the bank said in a statement.

"Identifying available office space is a necessary and predictable part of that contingency planning

process."

International banks have started to reveal more about their plans to shift jobs and set up new offices within the EU after Ms May indicated last week she’ll pull Britain out of the single market and pursue other arrangements.

Financial firms are most concerned about a "cliff edge" Brexit, whereby all access is cut off after two years.

Barclays staff moved to or hired in Dublin could include senior managers, derivatives specialists, currency traders, compliance and human resources staff, one of the people said.

The bank has not decided when employees will be moved or new hires made, with the timescale determined by how negotiations progress after Article 50 is triggered at the end of March, starting the formal two-year exit process.

The bank already has about 100 employees in the Ireland division, which is run by Sasha Wiggins from its office on the south side of the city centre.

Barclays’s 'Plan A' working assumption is that a deal will eventually be hammered out and British financial companies will not have to relocate services such as euro clearing to subsidiaries inside the EU, one of the people said.

Nevertheless, the lack of clarity means executives have to prepare for the worst, the people said.

The bank expects initial contingency planning to cost about £15m, including fees for lawyers and

real estate agents, the people said.

Bloomberg has previously reported Standard Chartered was also approached Irish officials about making Dublin its legal base inside the EU, people familiar with its discussions said in December.

Credit Suisse Group is also said to be exploring options to expand in Dublin.