GS spa, a chain of supermarkets owned by Carrefour with over 1,500 shops in Italy, and four of its directors, are under investigation for evading 64.72 million euros in VAT from 2018 to 2022, according to a decree issued by Milan prosecutors.

In a statement, Carrefour Italy said it was offering "maximum support and cooperation" to competent authorities, adding that the investigation concerned "deals with our logistics activities".

The alleged fraud, prosecutors said, was carried out by outsourcing and subcontracting logistics, cargo handling, porterage and transport services to "false cooperatives" - shell companies set up as cooperatives which did not pay taxes and social security contributions.

The phenomenon of labour contracting through dummy cooperatives has over the last five years been at the centre of other investigations by Milan prosecutors, targeting companies in the logistics, large-scale distribution and security sectors.

The decree concerning Carrefour mentions other investigations involving, among others, DHL Supply Chain, Uber, Ups, Fiera Milano and Esselunga.

The document alleges that GS spa illegally deducted more than 64 million euros in VAT through the invoices received from "false cooperatives", while the cooperatives evaded tax and social security payments worth in total some 110 million euros.

"GS spa's fraudulent conduct has been going on for many years and has resulted not only in the systematic exploitation of workers but also in considerable damage to the inland revenue," the decree said.

Last week, in a separate investigation into labour exploitation via indirect subcontracting to Chinese-owned workshops, Milan judges put a company of the Armani fashion group under judicial administration.

($1 = 0.9386 euros)

(Reporting by Emilio Parodi, editing by Alvise Armellini and Susan Fenton)