The Rail, Maritime and Transport union said that an equivalent of 1,000 services a year operate without a second member of staff.
The controversy has flared up ahead of tomorrow’s talks aimed at resolving a long-running dispute over the role of conductors.
Last month, during the industrial action, which included a ban on overtime by drivers, the RMT said that at least six times more Southern services were travelling without a second member of staff.
Now, the newest figures provided by rail workers and passengers claim to show that at least 26 trains didn’t have an on board supervisor despite promises made by bosses of Southern’s owners. This is an average of three services a day or 1,000 a year.
RMT general secretary Mick Cash said: “These figures confirm that as a bare minimum the equivalent of a 1,000 services will no longer have a second member of staff in addition to the driver.”
“That’s 1,000 journeys where a disabled passenger may not be able to get on or off the train or where passengers and the driver are at increased risk from anti-social behaviour or if something goes wrong, such as a derailment or fire.
“Guaranteeing a second member of safety critical staff on every train is the only way you can guarantee access for all and a safer journey for passengers,” he added.
A Southern spokesman said: “We said we would roster a second person to every train that has one today, and we are.
“However, we also said in exceptional circumstances when an on board supervisor is unavailable we will run the train as it is passengers’ interests to do so.”