Workers on Southern Railway are to stage a fresh strike in the bitter dispute over staffing and the role of conductors.
Members of the Rail, Maritime and Transport union (RMT) will walk out for 24 hours on April 4 – the 31st day of strike action since the row flared almost a year ago.
The announcement was made as members of the drivers’ union Aslef started voting on a deal aimed at resolving their dispute over driver-only trains.
RMT said it continued to press the company for a firm date for talks over the future role of the guard.
The union said it would reconsider its action to allow for talks to take place.
Mick Cash, RMT general secretary, said: “RMT members on Southern Rail have been fighting for safety and access for nearly a year now and it is disgraceful we have continued to be carved out of the talks process.
“It is a kick in the teeth for our members.
“This dispute needs to be pushed forwards and RMT would be prepared to reconsider our action if we get a commitment to a firm date for genuine and meaningful talks.”
The Aslef deal is being recommended by the union's leadership following talks with Southern's owners Govia Thameslink Railway.
Mr Cash said: “All parties should be at the negotiating table and RMT's continued exclusion means we have no option but to press ahead with further industrial action.
“It is now down to Southern/GTR, and the contract holders in the Government, to face up to their responsibilities and engage in genuine and serious talks to address our issues.”
A Southern spokesman said: “We’ve not received any correspondence from the RMT on this matter. When we do we'll review it and respond.
“In the meantime, they have announced a new strike date and we’ll plan accordingly if it goes ahead.
“We've been able to run over 90 per cent of our trains for our passengers on recent RMT strike days and we will plan to run a comprehensive service again.”
The new strike coincides with a home game by Championship football club Brighton.
Many fans travel to the ground on Southern services.