The Co-operative has been urged by general workers’ union GMB to end its relationship with Amazon citing concerns over the etailer’s ethical and trading policies.

The union has launched a campaign to press the Co-op to scrap the partnership, which has seen Amazon lockers installed in 160 of the grocer’s stores around the UK.

The GMB, which represents Amazon workers, said the lockers were a “cuckoo in the ethical nest” at the Co-op in a statement calling into question Amazon’s record over its employment terms.

The union said: “GMB has being warning the public that the high tech way Amazon process orders and tracks inventory disguises that it is also a traditional labour intensive mail order retail business”.

It described Amazon’s decision to discourage union membership and activity as “hostile”, adding that workers are forced to go “underground” to conduct meetings as a result.

GMB National Officer  Martin Smith said: “GMB need the support of Co-operative members to ensure that Amazon improves security of employment, treats workers fairly and pays them a wage they can live on in their distribution chain in the UK and elsewhere in the EU.”

The GMB represents some 620,000 British workers in across various sectors. Amazon employs 5,800 permanent staff, as well as a number of temporary workers and seasonal staff.

The Co-Op and Amazon both declined to comment on the GMB campaign.