The leader of Britain's main rail passengers' group has called on Tony Blair not to sack Stephen Byers to avoid causing further chaos on Britain's troubled railways.

The Secretary of State for Transport is braced for fresh calls for his head to roll tomorrow when new rail performance figures for the last quarter of 2001 will show that the punctuality of trains plummeted after he forced Railtrack into administration. But more recent figures show that Railtrack's performance dramatically improved from the end of December under the new management brought in by Mr Byers to sort out the chaos on the railways.

Francis Stewart, the chairman of the Rail Passenger Council, said: "The last thing that the industry and probably the British passenger needs is a change of Secretary of State. That would only delay the whole thing for another 12 months. He has got to see this through."

Separate figures will show that most delays are caused by the the train operating companies, rather than Railtrack, because of the lack of new rolling stock and drivers, and over-capacity on commuter routes.