RAIL chiefs have refused to guarantee that electrification of the line between York and Manchester will go ahead – warning that the cost is still unknown.

Flagship plans to electrify the trans-Pennine route – allowing faster, ‘greener’ services – are in jeopardy, an inquiry by MPs was told.

Funding was announced back in 2011 and work has already begun altering bridges on a project described as “vital” for economic growth by Network Rail.

But now the organisation has admitted there is no firm cost for the scheme – and, therefore, a risk that it may yet have to be delayed or scrapped.

Asked if electrification will definitely go ahead, Paul Plummer, Network Rail’s strategy director, told the Commons transport select committee: “I can’t give you that absolute, categorical confirmation.”

The admission is potentially embarrassing for George Osborne, who has vowed to deliver far more ambitious – and expensive – plans for a high-speed rail line across the Pennines.

The Department for Transport sought to play down the possible threat to electrification, saying it was confident its proposals were deliverable.