The activist at the centre of claims that London Stock Exchange chief executive Xavier Rolet is being forced out of his job has alleged the French CEO cannot tell investors the truth because of a confidentiality agreement.

Sir Christopher Hohn, who runs the hedge fund TCI Fund Management, made the claim in his second letter to LSE chairman Donald Brydon in less than a week. He has called for "all confidentiality agreements" on Rolet to be waived immediately.