A shipping union has accused Tesco and Shoprite of undermining Isle of Man ferry services by switching their freight to a company using low-paid eastern European seafarers.
Nautilus International, a union for maritime professionmals in the UK and Netherlands, has written to the two big retailers urging them to reverse their decision.
The Isle of Man Steam Packet Company uses the freight business to provide a subsided passenger route to the Island .
They are now facing competition from Estonian-flagged vessels run by a firm called Mezeron.
Nautilus general secretary Mark Dickinson said:"It is wholly unjustifiable that competition is introduced on the basis of ‘social dumping’ and undermining an established company that has a demonstrable commitment to decent working conditions and the employment and training of Manx and British seafarers."
RMT, Nautilus and Unite members will be handing out leaflets outside Tesco at Douglas on the Isle of Man on Saturday November 6.
Read the full Nautilus press release.