The independent rail regulator, Tom Winsor, yesterday appeared to contradict statements made to the House of Commons by transport secretary Stephen Byers regarding his role in the collapse of Railtrack.

Winsor, giving evidence to the transport select committee, said Byers had told him he would use emergency legislation to overrule the regulator if he took action to prop up Railtrack. In the Commons on Monday, Byers had said he did not "threaten" the regulator with legislation.

The Conservatives said that Byers' position was now "untenable".