DUBLIN/LONDON (Reuters) - Barclays (>> Barclays) has signed a lease agreement for more office space in Dublin as the bank prepares to expand its operations in the Irish capital to cope with the impact of Britain's exit from the European Union.

Green REIT , an Irish real estate development trust, said it had agreed a 20-year lease agreement to let two-and-a-half floors covering 3,437 square metres to the British lender in central Dublin, adjacent to the main shopping area of Grafton Street.

The bank will pay around 2.35 million euros (2.1 million pounds) in rent a year for the space.

Dublin and Frankfurt are emerging as the preferred choices so far for banks to relocate some of their London operations to as Britain prepares to leave the EU in March 2019.

Barclays said last month that it was in talks with Irish regulators about extending its activities in Dublin.

It already has a licensed entity in Dublin, Barclays Bank Ireland, employing around 100 people, which has a licence to conduct mainly corporate banking activities. It intends to extend the range of that licence so it can continue serving clients once Britain leaves the bloc.

Bank of America Merrill Lynch (>> Bank of America), which is one of Green REIT's current tenants in Dublin, has picked the Irish city to be its new EU headquarters.

JP Morgan Chase (>> JP Morgan Chase & Company) agreed in May to buy a building with room for 1,000 staff in Dublin's docklands area.

The U.S. bank has said it will use Frankfurt as the legal headquarters of its EU operations after Brexit, but that jobs will likely be spread across the bloc with some in Dublin.

(Reporting by Rachel Armstrong and Padraic Halpin; editing by Simon Jessop/Keith Weir)