Police searching for 'mystery' workers in Potters Bar crash

British Transport Police are looking for five railway workers who were seen on the Potters Bar rail track hours before last month's crash in which seven people died.

Officers appealed yesterday for help in identifying the "mystery" group – who were all wearing high-visibility orange jackets or tabards – in response to witness statements placing the men on the track at 8.25 on the morning of the crash.

Chief Superintendent Paul Crowther, of the BTP, said investigations had so far failed to trace the men. "It's an important part of the inquiry to talk to everyone who was at the area or who has done work in the area," Mr Crowther said. "There must be people within the industry who know something about this. We would very much like to hear from them."

The last carriage of the 12.45 West Anglia Great Northern King's Cross to King's Lynn service came off the tracks as it passed over them on 10 May. A preliminary investigation revealed that loose nuts on a set of points just before the station was the likely cause. The Health and Safety Executive said the points broke under intolerable stress because of the loose attachment.

Jarvis, the company responsible for the maintenance of the line, claimed last month that there was compelling evidence of sabotage. But British Transport Police said that was unlikely, although it still could not be ruled out.

Mr Crowther said the men detectives were seeking were at the site a few hours before the crash. "It's quite possible they were doing something completely unrelated but we need to establish what they were doing there," he said.

Police have spent several weeks trying to trace the men through Railtrack and Jarvis but without success.

A statement from Jarvis said: "Jarvis are providing the BTP with all staff transit movements in respect of the period when these individuals were seen. Our records account for all of our staff and we have found no record of any Jarvis personnel on or near the site at the time in question. No maintenance or other work was scheduled in this area for the time in question."

British Transport Police said the workers were seen a few hundred yards from the point where the train derailed. Statements have been taken from 2,100 people who have worked on the stretch of line recently.

A BTP spokesman, Simon Lubin, said that sabotage was still not being ruled out, but was unlikely. "It's not a likely scenario that five people in high- visibility jackets were out to sabotage a piece of line," he said.

Appealing to the workers to come forward, he added: "We would like to hear from them because it's important we speak to everybody who was there or thereabouts."

Railtrack officials said they were co-operating fully with the BTP investigation into the crash. They said in a statement: "Railtrack continues to assist the British Transport Police and the Health and Safety Executive and we have been working with them to try to identify people on the track that day. It is right and proper for Railtrack to provide information to the inquiry and wrong to speculate further."

One survivor, the author Nina Bowden, whose husband, Austen Kark, died in the accident, also dismissed the sabotage claims. Instead she blamed "poor maintenance, poor standards, cutting corners, all the sorts of things people do when they have no real feeling for the industry they are working in".

So far in the investigation, as well as speaking to more than 2,100 people, police have taken about 350 statements and tagged more than 800 exhibits.