The Enquirer understands that Northern Gas Networks is currently working on changes to its annual £63m replacement programme and will reveal full details in the New Year.

The move is a major blow to the big three contractors who were only awarded the deal in July to replace metal gas mains with plastic pipes.

Balfour Beatty was handed work in the the North East and northern Cumbria while Morgan Sindall and Enterprise work across Yorkshire.

A Northern Gas Networks spokeswoman said: “As a responsible organisation we are always looking for ways to deliver better value for our customers.

“As part of this, we are reviewing the delivery of our gas mains replacement programme with the full awareness of our contracting partners.

“Every year we invest around £63m to upgrade more than 528km of gas mains across the north of England, to ensure the continued safe and reliable supply of gas to our 2.6m customers.

“This work is carried out on our behalf by our contracting partners Morgan Sindall, Enterprise and Balfour Beatty as well as by our own direct labour teams.

“In the future we plan to increase the number of smaller subcontractors we use to deliver this work in the north of our region and expect to be able to announce details in the new year.”