Greater Anglia is investigating why train doors were allowed to open on the wrong side, allowing two passengers to disembark, on Tuesday.
The incident happened on the 1350 Peterborough to Ipswich service, which calls at Ely.
It took place while members of the Rail, Maritime and Transport workers’ union (RMT) were on strike regarding the future of guards on trains.
RMT general secretary Mick Cash has described the incident as “potentially disastrous”, saying it resulted from “strike breaking” staff members opening train doors on the wrong side, “resulting in passengers going onto the tracks”.
The union accuses the operator of breaching of their own and industry guidelines, requiring staff who perform conductor duties to receive 16 weeks training.
Mr Cash said: “Signals being almost passed at red, trains not being operated by driver’s due to safety concerns and now passengers getting out of the wrong side of the train and onto the tracks.
“This is all because Greater Anglia are determined to break the strike at any costs by using staff who have had a few days training rather than the four months required by the company’s own standards.
“Now following the revelations of safety breaches reported by the media Greater Anglia have jeopardised safety further by taking down their own internal daily log which reports safety breaches. They are trying to hide the threat to safety from staff and passengers alike and we are therefore calling for full public disclosure of all safety breaches.”
RMT have raised their concerns with the safety regulator, as well as Greater Anglia’s owners, Dutch state railways.
Greater Anglia is conducting an investigation into the latest incident and following :all usual safety procedures”, service delivery director Richard Dean said.
“We have been operating a safe service throughout the strike… Our stand-in conductors have been fully trained and had to pass safety, competency and medical tests. They safely operated over 500 services on Tuesday.”
No one was injured during the incident, which took place in a terminating platform next to a fence after the train had arrived at Ipswich station on Tuesday, October 3.
Greater Anglia said the doors hadn’t automatically opened but were released so that if passengers pressed the button they would open.
Two people got out of the train on the side of the fence and onto the platform.
Correct safety procedures were then applied and all other passengers got out onto the platform on the right side of the train, Greater Anglia said.
