The Sunderland North MP took to the streets with RMT transport union members to call on Wearsiders to fight to keep Metro as a public-run service.

"The Metro system is the most successful light railway in Britain, and I was always taught that if something is working, then leave it alone," he said.

"If it isn't broken, don't fix it."

Tyne and Wear transport authority Nexus, which runs the Metro, has invited private firms to bid for a contract to run the day-to-day operations and maintenance of trains and stations on its behalf.

Nexus says it will continue to own and manage Metro, set fares and monitor performance. It is also investing more than £320million in modernising the 74km network, and is putting in an in-house bid to run the system itself.

But Mr Etherington, speaking in a rally on High Street West, in Sunderland city centre, yesterday, said the move was privatisation in all but name.

"I have seen what happened with British Rail (when they privatised that)," he said.

"We have the highest fares in Europe, working conditions for staff got worse, five times as much public subsidy was needed and large profits were being made."

The MP said the same thing would happen with Metro.

He said Sunderland had waited a long time to see the service extended to Wearside and it would be a shame if services got worse because a private firm was brought in to run it.

"The Government are for it, Labour are for it – but I'm not. I can't think of an example where privatisation has been an improvement," he said.

Stan Herschel, North East organiser for the RMT, said: "The Metro is not there to make a profit, it's there to provide a public service to people."