The boss of Thomson and First Choice owner TUI said the beach massacre in Tunisia that claimed the lives of 33 of its customers was the “most tragic” event in his 30-year career as the group laid bare the financial impact of recent terrorist attacks.

Travel companies have offered tourists the chance to change their holiday bookings to Tunisia in light of today’s attack in Sousse which left at least 28 people dead including a number of Britons, Germans, Belgians and an Irish woman.