Horrified council food safety watchdogs discovered a mattress propped up in the back of a fly-ridden chicken shop in the Forest Gate.

It was being used by staff to get some sleep while they worked long hours for a pittance, said the council.

It’s a stark example of why Newham Council say it has been working with the UK Border Agency, the police, tax inspectors and the Department for Work and Pensions (DWP) to crack down on the widespread exploitation of staff at chicken shops throughout the borough.

The council says it has long been aware that there is “chronic underpayment” of staff and massive problems with working conditions at the hundreds of chicken shops.

However, it does not have the power to mount raids on suspicion of non-payment of the minimum wage. Instead, it has had to couple wage investigations with hygiene checks – because it has the right to enforce health and safety regulations – or to persuade central government tax inspectors to co-ordinate joint investigations.

Newham Mayor Sir Robin Wales said: “The introduction of the National Minimum Wage is widely regarded as one of the most impactful policies of recent decades.

“However, what many people do not realise is that there is a hidden economy operating where workers are still not receiving the NMW. Without improved enforcement of the law these abuses will continue. “In Newham, we know that paying below the NMW is not just bad for the workers who get exploited, it’s bad for businesses and the local economy. As the informal economy booms so legitimate businesses and good jobs diminish.

“It’s vital we tackle unscrupulous employers, create a level playing field for businesses to operate and enforce the law designed to protect workers . As a local authority we are out and about in our community every day on the front line, working with businesses, employers and employees.

“Local authorities are best placed to challenge businesses who are not paying their employees the full NMW. That is why I am calling on the Government to give us the investigative powers to deal with this problem head on.”