A project to build Britain's first mainline steam locomotive in 40 years has been rocked by allegations that it may never take to the tracks because of safety concerns.

Now the trustees overseeing the £1.7m scheme are expected to face a confidence vote at an emergency meeting on Saturday.

Work on the A1 Pacific Tornado, now under construction at the Hopetown engineering works in Darlington, has been ongoing since 1990 and is expected to be completed by 2003.

But a letter sent to the A1 Steam Locomotive Trust's 1,500 covenantors - who make regular contributions to fund the scheme - claims that serious flaws in the construction mean the Tornado would be unsafe unless remedial work is carried out.

The letter also claims that the Board of Trustees has kept covenantors in the dark over the concerns, and that this is linked to the resignation of the trust's legal advisor, Stuart Palmer.

Trust chairman Mark Allatt rejected the allegations and insisted the project was still on course.

The allegations were made in a letter written by Keith Bottomley, a covenantor who has also carried out electrical work on the Tornado.

Mr Bottomley said a survey carried out two years ago identified serious faults in the construction, which would prevent the Tornado ever coming into service.

He said: "I want the board to explain to us whey the haven't picked up on these faults and what they propose to do about them."

Mr Bottomley said one of the faults was in the fitting of a buffer beam, which meant the locomotive would be damaged the first time it came buffer-to-buffer with a train. He added: "My contention is that all these things should be put right urgently before we proceed any further."

Former legal advisor Mr Palmer said: "I resigned for a number of reasons but I would rather not comment.

Mr Allatt said Mr Bottomley's allegations were "complete nonsense". He insisted there were no outstanding problems over the Tornado's construction.

A survey had revealed some faults but all but one were minor and they had been put right

"It is being checked at every stage by the relevant authorities and it has passed every test," he said.

"There is nothing wrong with the design but when you are building a steam locomotive 40 years after the last one was built, there are going to be some problems."

Mr Allatt said he had written to covenantors to address concerns raised in Mr Bottomley's letter and Saturday's meeting was a chance for any outstanding issues to be covered.

He added: " I find this whole episode extremely frustrating. I have had a number of covenantors ring up who are obviously concerned and all these sorts of things are extremely damaging for the project."