A railway operator being hit by industrial action has been accused of cancelling trains despite crews being available.
Southern Railway services are being disrupted by an overtime ban by drivers in the Aslef union in a long-running dispute over driver-only trains.
But union officials said trains from Eastbourne to London were cancelled this morning even though train crew were available.
One worker sent a message to a colleague which said: "Southern have CANCELLED all London trains and Brighton trains, yet the crews are in the mess room.
"They have had their diagrams changed when they booked on for work."
Mick Cash, general secretary of the Rail, Maritime and Transport union (RMT) said: "It is total chaos on Southern Rail again this morning with the company misleading the public and mismanaging their staff resources.
"This is not the first time this has happened and it lays bare the complete and utter shambles on the Southern contract.
"It's about time Transport Secretary Chris Grayling and his Government took some responsibility and ended this fiasco once and for all."
Among those disrupted by the cancellations were people planning to attend the anti-Government protest in central London.
RMT members are staging a 24-hour strike on July 10.
A Southern spokesman said: "The Aslef overtime ban means we have no choice but to reduce the number of trains planned to give our passengers a robust timetable.
"Where additional crew is available, we are using them wherever possible to run extra shuttle services, for example today between Haywards Heath and Lewes.
"Passenger numbers have doubled on Southern in just 12 years and we have to modernise infrastructure, trains and working practices to address the capacity crunch for passengers.
"We want the unions to support us in this endeavour."