John Longworth, the director general of the British Chambers of Commerce (BCC), has resigned following his public support a Brexit.
With its membership split, the BCC has officially said it will take no side in the debate. But the organisation suspended Mr Longworth following a speech last week in which he said the UK's long-term prospects could be "brighter" outside the EU.
The BCC said Mr Longworth's personal opinion on the debate was "likely to create confusion". Mr Longworth himself said that stepping down was the "right thing to do".
BCC president Nora Senior: "John Longworth and the BCC board recognise that John's personal view on the referendum is likely to create confusion regarding the BCC's neutral stance going forward.
"In light of this, John has taken the decision to step down as director general and his resignation has been accepted by the board with effect from 6 March 2016."
Ms Senior did not reveal whether or not Mr Longworth received a pay-off, but she stressed that his resignation is not the result of political pressure from the 'In' campaign.