On the eve of tomorrow's fourth anniversary of Metronet assuming control of infrastructure on the Bakerloo, Central, Victoriaand 'sub-surface' lines, RMT called for an end to an end to the PPP experiment that had "failed by every measure".

"Metronet and Tubelines have already snaffled more than £3.3 billion of public money and made £300 million in profits, yet they are failing to meet even the modest targets they were set," RMT general secretary Bob Crow said today.

"The PPP years have been marked by deterioration in service, missed targets, infrastructure failures, engineering overruns and an alarming rise in safety problems.

"Now Metronet's costs are soaring out of control and they are threatening to scale back renewals work even further if they are not handed even more public money to offset £750 million in cost overruns.

"That is also no doubt why they are trying to split up their workforce and outsource contracts, adding even more fragmentation to the chaos they have already created.

"We have said time and again that failure and fragmentation are built into the very fabric of the PPP, and the time has come to call a halt to a scam that is little more than a complex device for converting taxpayers' and farepayers' money into super-profits.

"If London is to get the world-class Tube system it needs for the 2012 Olympics it is abundantly clear that the PPP should be scrapped altogether and the work brought back in-house," Bob Crow said..