High-street fashion retailer Zara is under investigation (for the second time in the recent past) for unethical labor practices. This time: the use of slave labor at factories in Argentina. Today, immigrant workers, including children, were discovered producing clothes for the label in “degrading” sweatshop conditions, investigators said. The mostly Bolivian laborers claimed they were made to work more than 13-hour days and were prevented from leaving the factories without permission. Garments being sewed at one clandestine workshop in Buenos Aires included items from the Zara Man collection.

Juan Gomez Centurion, the head of the country’s Government Control Agency, which raided three factories producing Zara clothes last week, said: “We found men and children who lived in the place where they worked. They were not registered and they were living in terrible conditions. They had no official documents and were held against their will, they were not allowed to leave their workplaces without permission.”

Authorities moved in on the sweatshops in the outlying Mataderos, Liniers and Floresta districts of the Argentine capital after a tip-off from workers’ rights NGO La Alameda. The charity’s spokesman Gustavo Vera said people at the factory were made to start at 7am and work without a break until 11pm, from Monday to Saturday. He said: “Their workplaces were also their homes, families were forced to share cramped quarters in a mess of sewing machines, needles, threads and children. The places were dark without proper lighting to sew and no ventilation.”

The Spanish company behind Zara, Inditex, said today they were “surprised” by the revelations and claimed they had not been officially notified by the Argentinian authorities. A spokesman said: “From the limited information we have, which are the addresses of the workshops, they have no relationship with our suppliers and manufacturers in the country.” He added that Zara has 60 Argentinian manufacturers and in the last two years conducted 300 audits of suppliers and factories, but would cooperate with any investigation. It is the second time Zara has been accused of involvement in slave and child labour in South America.

In 2011 a group of workers – 14 Bolivians and one Peruvian – were rescued from an unlicensed factory in Sao Paulo, Brazil, where clothes carrying the Zara label were being produced. The immigrant workers, one of whom was reported to be just 14, were living in dangerous and unhygienic conditions, forced to work 12-hour shifts for between £95 and £176 a month.