Lloyds is the latest bank to issue a warning over Brexit.
The banking group warned of economic uncertainty and short term volatility, while the long term impact was unclear.
The group which runs Lloyds, Halifax, Bank of Scotland and Scottish Widows and is the UK's biggest retail bank with 30m customers said in a statement:
"The board of Lloyds Banking Group has considered the potential implications of the EU referendum for the group, its customers, colleagues and shareholders, and for the broader economy. The referendum and a vote to leave the EU are likely to cause economic uncertainty and potential volatility in the short term. With no certainty over how the UK’s position outside the EU would evolve, the longer term economic impact is unclear.
The Board is mindful that the future of the UK’s relationship with the EU is a matter for the UK electorate, and that for many the debate is about more than just economics. Lloyds Banking Group will maintain its focus on being the best bank for customers and shareholders, and will continue to support its customers, irrespective of the referendum outcome."
Boss Antonio Horta-Osorio had said in February the bank's board would consider the impact of Brexit at its next board meeting.
Lloyds has taken a more conservative tone than HSBC, which warned in February of a labour shortage, food and retail price rises and harm to the banking industry.
The official position of the bank is in stark contrast to that of chairman Lord Blackwell who has been a vocal backer of Brexit.