Merging the German container shipping line Hapag-Lloyd with Neptune Orient Lines of Singapore would be a coup for Tui chief executive Michael Frenzel – and yet a deal, if struck, might only amplify calls to split up his company.

The combination would produce a fifth global container shipping group – serving leading ports in Europe, the Americas and Asia – and sit in Tui’s portfolio alongside 51 per cent in Tui Travel, Europe’s market leader in tourism.