Plans to spend an extra £15 billion of taxpayers’ cash on Britain’s roads were announced yesterday as ministers fatten the network up for privatisation if the Tories win next year’s general election.

The government boasted of the “biggest, boldest and most far-reaching roads programme for decades.”

The extra spending comes on top of an estimated £40bn in public money already being paid to contractors to upgrade 4,000 miles of Britain’s motorways and other major roads.

Labour hit back that no new money had actually been pledged, branding it “yet another re-announcement” on improvements.

At the same time the Tories and their Lib Dem collaborators are introducing new regulations through a Bill which will change the Highways Agency — currently part of the Department for Transport — into a government-owned company.

Civil servants’ union PCS believes the move is a first step towards privatisation of the road network.

Workers at the agency, which already passes road maintenance work to private contractors, are members of PCS.

PCS general secretary Mark Serwotka told the Morning Star: “We are very concerned that our roads are being primed for full-scale privatisation along the lines of our rail network, and that this investment is in effect a public subsidy of profit-making companies.”

The new investment includes £1.5bn to be spent on adding extra lanes to some motorways, while improvements to junctions on the M25, the A27 in Sussex, to approaches to Liverpool and to the A1 in the north-east of England are also planned.

The commitment to spend so much taxpayers’ cash comes within 24 hours of revelations that the government will need to borrow another £75bn because its austerity economic policy is not working thanks in part to plummeting income-tax revenues.

Current highways spending includes conversion of motorways into “managed motorways” or “smart motorways,” with the installation of new traffic controls, electronic direction indicators and variable speed limit signs, dozens of cameras to monitor traffic and systems to divert drivers on to hard shoulders at times of heavy traffic.

Bosses’ organisation the Confederation of British Industry has welcomed the new spending.