A decision on whether or not a major upgrade of the A66 to full dual carriageway will go ahead has now been delayed until March next year.

Transport Secretary Mark Harper had been due to rule on the £1.3bn scheme on Tuesday, but in a written statement to Parliament on Wednesday, it was confirmed the deadline has now been extended to March 7, 2024.

The notorious 50-mile stretch from Scotch Corner at the A1(M) in North Yorkshire to Penrith on the M6 in Cumbria is a dangerous mixture of single and dual carriageway.

A huge consultation and planning exercise has been carried out by National Highways over the past four years and work was due to begin on the scheme to finally transform the route into a full length dual carriageway next year, pending the final go ahead by the Government.

Darlington and Stockton Times: The A66 changing to single lane in North Yorkshire Picture: SARAH CALDECOTT

Inspectors appointed to look at scheme issued a recommendation to the secretary of state on August 7, giving him until November 7 to make a decision.

Wednesday's statement, from Huw Merriman, Minister of State at the Department for Transport, said: "It has been necessary to extend the deadline for the decision on the application by National Highways under the Planning Act 2008 for the A66 Northern Trans-Pennine Development Consent Order (DCO).

"The deadline for the decision is to be extended to March 7, 2024 (an extension of four months).

"The reason for the extension is to allow for further consideration of matters including those not resolved at the time the examining authority’s report was received by the Secretary of State. This will include the consideration of information submitted by the applicant regarding impacts on the North Pennine Moors Special Area of Conservation, to ensure compliance with the Conservation of Habitats and Species Regulations 2017.

"The decision to set a new deadline is without prejudice to the decision on whether to give development consent for the above application."

Earlier this year, fears emerged that the scheme could be in doubt amid rising costs, sparking calls for the Government to ensure the scheme went ahead on both safety and economic grounds.