The release of Railtrack documents during the chancellor's pre-Budget statement has resulted in further criticism of transport secretary, Stephen Byers, and his special adviser Jo Moore.

It has emerged that the Downing Street strategic communications unit, headed by Alastair Campbell, was so angered by the decision to release a crucial Railtrack document during Gordon Brown's presentation of the pre-Budget report that it sent a strong letter to the DTLR protesting at the subsequent "contamination" of the pre-Budget Report's press coverage.

Meanwhile Liberal Democrat leader Charles Kennedy added his voice to the chorus of criticism.

He told the Today programme: "I think there is a degree of corrosion that is taking place here politically where Stephen Byers is concerned over a variety of issues. He is looking like damaged goods."