The bank, which is 73% state-owned, issued the guidance this week. It is the latest financial business to remind staff not to offer views that could influence the way individuals vote.
In April, Goldman Sachs told its staff not to distribute materials that could be seen as campaigning for either outcome in the referendum. The guidance from the US bank was issued on 15 April, when Electoral Commission rules required businesses publishing research relating to Brexit to show their intention was not to influence the result.
Reuters has reported that Bank of America Merrill Lynch emailed its employees last week to encourage them to register to vote in the referendum on 23 June and provided website links to logistical information about how and when to vote.
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