The not-for-profit company planned as the successor to Railtrack is to receive government backing in order to make it attractive to investors.

The most likely option is a government loan facility, while increasing charges to the train operating companies, who pay to use the tracks, is also a possibility. The train companies would be reimbursed through higher government subsidies.

The Financial Services Authority chairman, Sir Howard Davies, yesterday rejected Conservative calls for an investigation into the handling of the collapse of Railtrack. He said he had no mandate to comment on the government's actions, and that if there had been any impropriety it would be up to the government to prosecute itself.