Workers on Southern rail are to stage a fresh strike in the long-running staffing dispute after the collapse of talks.

Members of the Rail, Maritime and Transport (RMT) union are to walk out for 24 hours on 22 February, threatening fresh travel disruption for Southern’s 300,000 passengers.

The two sides met at the conciliation service Acas on Tuesday, but the row over the role of conductors remains deadlocked.

Leaders of the drivers’ union, Aslef, reached a deal with Southern’s owner, Govia Thameslink Railway, earlier this month in a separate row over driver-only trains, which its members have been voting on, with the result due on Thursday.

The deal was reached after 11 days of talks co-chaired by the TUC.

Mick Cash, RMT general secretary, said: “The abject failure by Southern rail in yesterday’s talks to take the safety issues seriously has left us with no option but to confirm further action.

“These disputes could have been settled if Southern had listened to our case and given the guarantee of a second safety-critical member of staff on their trains.

“Instead they have shifted the goalposts even further and have now created a ‘strike-breakers’ charter’, where one of the numerous new conditions where trains can run driver-only is during industrial action.”

Cash added: “The full detail of Southern’s plan is far worse than anyone could have anticipated. This is dire news, not just for staff but for passengers, who rightly demand a safe, reliable and accessible service.

“It is now down to Southern to face up to their responsibilities and engage in genuine and serious talks that address our issues.”