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.

The bank started scouting the city for office space this month and has been in contact with Irish regulators about expanding its operations, said the people, who asked not to be identified because the plans aren't public. Barclays is moving ahead with contingency plans so it can continue serving EU clients if 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 offices within the EU after May indicated last week she'll pull Britain out of the single market and pursue other arrangements. Financial firms, and their clients, are most concerned about a "cliff edge" Brexit, whereby all access is cut off after two years. Ireland has been seeking to lure banks based in Britain by presenting itself as a low-tax, English-speaking location with similar laws, regulations and "passporting" rights, enabling them to sell services across the EU.

Credit Suisse Group is also exploring options to expand in Dublin, people familiar with that bank's plans said. The lender made the city its primary hub for servicing hedge funds in Europe last year, when Irish Prime Minister Enda Kenny opened the firm's trading floor. The Swiss bank may have to get regulatory approval to upgrade its branch to a full subsidiary, whereas Barclays already has that status.

Dublin is emerging as a favoured location for Credit Suisse's so-called back-office jobs, said one of the people. The Zurich-based bank also is considering cities including Frankfurt as it develops Brexit plans for moving jobs, said the person.

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. Executives haven't 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 lender already has about 100 employees in the Ireland division, which is run by Sasha Wiggins from its office in the city centre. Barclays also has a banking license in France, a branch in Germany and many legal entities in Luxembourg, according to company filings. A spokesman declined to comment on its European staffing plans.

Standard Chartered has also approached Irish officials about making Dublin its legal base inside the EU, people familiar with its discussions said in December. Citigroup is evaluating the capital along with other cities, European regional chief Jim Cowles said this week, while Lloyds Banking Group is set to establish its EU headquarters in Frankfurt.

Barclays's "Plan A" working assumption is that a deal will eventually be hammered out and British financial companies won't have to relocate services such as euro clearing to subsidiaries inside the EU, one person 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 £15 million, including fees for lawyers and real estate agents, the people said.

Chief executive officer Jes Staley has struck a more sanguine tone on Brexit than his peers, saying it's going to be "very difficult" to move an established financial centre like London elsewhere. His comments compare with warnings from JPMorgan Chase & Co CEO Jamie Dimon, who said last week "it looks like there will be more job movement than we hoped for". Dimon had previously said he'd move 4000 people from the UK after Brexit - while HSBC Holdings and UBS Group have said at least 1000 London staff may be relocated.

Still, Staley said clarity is needed about whether the UK is seeking a longer transition period, arguing a "a two-year cliff is not helpful for anybody" in a Bloomberg Television interview at the World Economic Forum in Davos last week. Barclays may reassign its Frankfurt branch to report into its Irish subsidiary and some traders could be moved to Dublin if certain activities need to be booked inside the EU, he said.

The bank is expected to provide an update on its Brexit contingency plans with its full-year results on February 23.