(Adds details from memo, background on other banks' Brexit plans)
LONDON, July 20 (Reuters) - U.S. bank Citigroup said on Thursday that it may need to create 150 new jobs in the European Union to deal with the impact of Britain leaving the bloc, as it confirmed it would headquarter its EU trading operations in Frankfurt.
Citi is one of several banks opting to build up a subsidiary in Frankfurt so that its trading operations in the EU can continue without too much disruption when Britain leaves in March 2019.
"Frankfurt is our first choice for headquartering our EU broker-dealer based on the existing infrastructure, and the people and expertise we already have on the ground," Jim Cowles, the bank's head of Europe, Middle East and Africa (EMEA) said in a memo to staff.
He added that the bank also planned to build up its private banking, treasury and trade and investment banking businesses in the EU.
This would be done by "increasing over time our footprint in other key EU cities including Amsterdam, Dublin, Luxembourg, Madrid and Paris."
Cowles added that the bank's London office would remain its EMEA headquarters.
Details of banks' Brexit arrangements are starting to emerge following a July 14 deadline for them to submit details of their contingency plans to the Bank of England.
A source told Reuters on Wednesday that Morgan Stanley had also chosen Frankfurt as a base for its EU trading operations, while Barclays said last Friday that it was in discussions with regulators about building up its operations in Dublin.
Banks have indicated that while they may pick one EU center to be their main regional subsidiary in the bloc, they are likely to spread their operations across several countries.
JPMorgan CEO Jamie Dimon said on July 11 that his bank would probably use Frankfurt as the legal domicile of its European operations after Brexit, but that jobs may be put elsewhere as well. (Reporting by Rachel Armstrong, editing by Maiya Keidan and Adrian Croft)