A fresh row over staffing on the railways has broken out after a union said it had "conclusive evidence" that a leading train operator was deliberately cancelling services and blaming staff sickness.
The Rail, Maritime and Transport union (RMT) has written to the managing director of Southern Railway accusing the company of "lying" to passengers over the reasons for a spate of cancellations in recent weeks.
The union quoted two examples it claimed showed how Southern was trying to shift the "scandal of short-staffing and managerial incompetence" onto front-line workers.
The letter says a driver and guard were available to work the 7.10 Brighton to Lewes on June 1, and arrived, in good time, only to find the train was showing as cancelled due to a shortage of train crew.
The second example involved a Twitter response from Southern to a passenger saying a train had been cancelled due to a shortage of guards, when the line used driver only trains.
The RMT said there was a "deliberate" shortage of 43 staff which was "blowing a hole" in roster patterns.
RMT general secretary Mick Cash said: "RMT will not tolerate the disgraceful attempts to blame the current operational crisis at Southern on the front-line staff when the responsibility lies with those at the top and their gross mismanagement of this basket-case franchise.
"The company are caught our red-handed today cancelling services that were fully staffed and blaming the guards for the cancellation of services that don't even have guards on board. That is conclusive proof that the company are engineering the current shambles so that they can knock lumps out of their own staff.
"Southern should stop the dirty tricks and start talking with us in a serious and responsible manner."
Southern said the Brighton-Lewes service was cancelled because the company thought the staff were unavailable.
When they did turn up, it was too late to reinstate the service.
The other case was someone on Southern's Twitter team ?simply giving erroneous information as to the reason for the cancellation in a "genuine error", said the company.
Southern said it is cancelling up to 90 trains a day because of staff sickness.
The two sides are embroiled in a bitter row over the role of conductors, which has led to strikes, and remains unresolved.
The company won a legal case last week against a strike ballot by the drivers' union Aslef in a separate dispute over driver only trains.
A Southern spokesman said: "Both of these cases were nothing more than simple human error.
"In one, a train was cancelled because we wrongly thought the crew were not available. By the time the crew arrived for the service, it was too late to reinstate it. ?In the other instance, an incorrect explanation was inadvertently given as the reason behind a cancellation.
"Both of these mistakes are regrettable, but must be seen in the context of unprecedented levels of staff sickness resulting in more than 80 train cancellations each day, and putting pressure on the staff who are at work.
"The accusation that we are deliberately cancelling services is quite simply ludicrous."