French fabricator Sendin has supplied pre-assembled steel reinforcement panels for the diaphragm walls forming two of the critical ventilation shafts on the Chiltern Tunnels section of the vast project.

It will also deliver further assemblies to the same section over the coming months.

HS2 claims the decision was taken to use the rebar fabricator because no other UK supplier could provide the necessary steel.

The volume of steel rebar awarded to Sendin is estimated at less than 5% of the total rebar used on Align’s section of the HS2 project.

A spokesperson for HS2 Ltd said: “The original supplier of this steel reinforcement was UK-based, however this supplier was unable to maintain the agreed programme – forcing potential delays and therefore higher costs on the project.

“Our contractor approached all suitable alternative UK suppliers, but none could provide the necessary product in time.

He said: “The French fabricator Sendin is an internationally renowned supplier in this market that had previously held full UK certification and is in the process of being re-certified.

“They were able to respond quickly, allowing the project to stay on schedule. HS2 Ltd continues to work with UK Steel to provide updates on opportunities and broker relationships between its members and the HS2 supply chain.”

But British fabricators complain that the move conflicts with HS2’s own specification stipulating the need to use UK CARES approved fabricated reinforcement.

They also are concerned that the UK CARES certification body failed to act promptly to police the situation after being alerted back in March.

Stephen Elliott, Chairman of the British Association of Reinforcement, said there was ample UK rebar to supply demand in the market.

“HS2 is a major UK project being paid for by the UK public. It is, therefore, disappointing that HS2 is not ready to fully support the UK steel industry,” he said.

“We had hoped that UK major projects will work with, and not undermine, the UK steel industry.”

He added: “Of equal disappointment is that, despite being alerted to the importation of non-approved reinforcement, UK Cares has yet to make a formal public statement.

“CARES must been seen to police its own scheme, if it wants to stop another major project going down the same route.

Elliott added: “But nine months on since the CARES was first alerted such retrospective approval is rather like shutting the stable door after the horse has bolted.”

Fabricator Sendin is certified to meet the French AFCAB steel reinforcement certification scheme.

But rivals say it does not hold UK approval for reinforcement cutting and bending and reinforcing bars as the French standard does not meet the requirements of BS 4449 particularly in respect of the specified fatigue properties.

Nor does it hold UK approval for the application of the specified TA1-A reinforcement couplers.

Trade body UK Steel’s Director General, Gareth Stace, said: “It is hugely disappointing to see HS2 failing here to take the most basic step of using of steel made to British Standards.

“Such practice is practically universal practice across the UK construction sector, HS2 would have almost had to go out of its way not to use British Standard steel.

“In doing so, HS2 has missed a vital opportunity to support UK jobs and economic growth through its spending of taxpayer’s money.”

A spokesman for UK CARES said: “CARES continues to work closely with all its clients – in particular those engaged in major public sector infrastructure projects where safety, quality and sustainability standards are paramount.

“Those clients recognise that CARES certification is only achieved as a result of robust, wholly independent assurance processes which operate across a dynamic global steel supply chain.”