The lives of other workers: store detective says Aldi wanted him to spy on staff

A private detective who worked for the German discount supermarket chain Aldi has accused it of using Stasi-style surveillance tactics – including hidden cameras – to spy on staff and gather information that could be used against them.

The claims were published by the news magazine Der Spiegel, which said its unnamed informant was employed by Aldi for years to help it combat shoplifting. The whistleblower said: " I had to report everything that came to my attention. I had to say if an employee was working too slowly, engaged in having an affair and reveal other private details such as their financial situation."

Aldi flatly denied the allegations yesterday and insisted that its store detectives were expressly forbidden to use surveillance techniques to assess staff performance. It said it had not issued any instructions to find out personal information about staff.

Similar accusations were made against Aldi earlier this year by a former manager, Andreas Straub, who quit in disgust over management practices that he described as a "system of control and fear".

In his book Aldi – Simply Cheap, Mr Straub accused the chain of blackmailing, threatening and coercing workers it wanted to get rid of. Mr Straub said that after publishing his book, he received an anonymous phone call in which he was told: "Shut your face – we will make you pay for this."

In 2008, managers at Aldi's German rival Lidl were said to have intimidated and bullied their staff. In one case, a woman cashier was refused permission to leave her till to use the lavatory. Lidl subsequently apologised.