It has emerged that jobseekers in the government’s work programme were asked by the Close Protection UK (CPUK) security firm to sleep under London bridge before stewarding the Queen’s Diamond Jubilee celebrations.

The prime minister’s spokeswoman dismissed criticisms of the incident by insisting that it had been a “one-off”.

“This is an isolated incident. The company has apologised,” she said.

The government’s work programme arranges for companies and charities to provide people on jobseeker’s allowance with unpaid work experience.

Two jobseekers who worked for free over the Jubilee and asked not to be named told the Guardian newspaper that they had to camp under London bridge overnight and had no access to toilets for 24 hours.

The TUC said that the “appalling treatment of staff” demonstrated “the damage that unpaid work experience risks causing people who are desperate to get back into proper employment, as well as the exploitative treatment that they can face”.

Managing director of CPUK Molly Prince told BBC Radio 4: “The whole situation has been exaggerated and we’re talking about two or three people complaining out of 220 staff that were supplied to the event.

“It was badly handled and for that we’ve extensively apologised. We’re not in the business of exploiting free labour.”

But a member of the Labour group on the London assembly, John Biggs, insisted: “It is simply unacceptable in the 21st century for people to work unpaid and be forced to sleep outside. The company have tried to blame a logistical mistake, but the simple fact is they had a duty of care to their workers and they failed.”

Image: Getty