Negotiations to try to drive down extra costs added to the bill for the Norwich Northern Distributor Road must not be used as “smokescreen” to keep the public in the dark, the opposition leader at County Hall has warned.

Norfolk County Council members have admitted there is now a “high risk” of a “significant” hike in the cost of the road - but they remain tight-lipped about just how many millions could be added to the bill.

Delays and the need for changes to some elements of the work on the £178.5m road have pushed up the costs, but the precise figures involved have been kept under wraps.

The council says that has to be the case because the council will be negotiating with its contractors Balfour Beatty in an attempt to keep the costs down - a process which could go on for months.

But Steve Morphew, leader of the Labour group at the city council said “very searching questions” needed to be asked of the political management of the contract.

He said: “The Conservatives have a poor track record on major schemes - it is hard to forget the incinerator.

“Not far down the track are more critical infrastructure schemes like the Western Link, A47 dualling, Long Stratton Bypass and third river crossing for Great Yarmouth.

“These are very expensive projects and the public is entitled to reassurance that those responsible for overseeing the schemes are doing their jobs properly.

“It is right the council doesn’t compromise its negotiations with the contractor and Labour will support a robust position, but that can’t be allowed to be a smokescreen for keeping people in the dark.

“In the recent county council elections the Tories said they would look after Norfolk’s money. So far there isn’t much evidence of that at a time when every penny needs to be put carefully to work for Norfolk people.”

Martin Wilby, chairman of the council’s environment, development and transport group stressed the road, which will stretch from the A47 at Postwick to the A1067 Fakenham Road, still had the support of councillors.

And he said his committee had set up all-party working group to support that, and to ensure the experience gained is applied to future major projects, maximising the return on public investment.