Image copyright Merseytravel Image caption Merseyrail plans to introduce a new fleet of driver-only-operated trains from 2020

Staff on Northern, Southern rail and Merseyrail have voted to strike in a dispute over the role of guards.

The RMT union announced the walkouts in a dispute with the firms over plans to remove guards from trains, which would become driver-only-operated (DOO).

Union officials, who confirmed the 24-hour strike on 13 March, say the move will make trains potentially dangerous.

The Office of Road and Rail insists they are safe provided the right equipment and training is given.

As well as walking out on strike, Merseyrail members will also not work any "rest days" from Monday 7 March indefinitely.

RMT general secretary Mick Cash said the result "sends out the clearest possible message" that the union "is prepared to stand up and fight for public safety and the guard guarantee".

He said the union's position on DOO "is perfectly clear" - "we will not agree to any introduction of DOO".

Image copyright PA Image caption The dispute is over who is responsible for opening and closing the train doors

Arriva Rail North, which operates Northern trains, provides services across the north of England.

Merseyrail plans to introduce a new fleet of 52 (DOO) trains from 2020 and said none of the permanent guards or guard managers would lose their jobs.

The union said more than 81% of members at Northern and Merseyrail voted for strike action and more than 93% voted for action short of a strike.

A spokesman for Northern said the strike announcement "is a shame" and the firm's "aim is to reach a constructive resolution" and "protect jobs and pay".

A Merseyrail spokeswoman said the firm has "pledged to do everything we can to bring the dispute to a satisfactory and swift conclusion" and is "committed to continuing dialogue with the RMT".

Image copyright PA Image caption Southern rail passengers have faced months of delays and disruption

Mr Cash said the union had no option but to strike again following "the abject failure by Southern rail to meet with us".

But, Southern said: "They say they want to talk, but they are hell-bent on further strike misery and causing disruption."

Parent company Govia Thameslink Railway (GTR) said news of a further strike on what would be the 30th day of RMT strike action was "clearly disappointing".

"We asked the RMT executive to suspend any further action... so that talks could take place, instead they have chosen to put their members through even more pointless industrial action."

Last week, the drivers' union Aslef met Southern for talks after its members rejected a deal.

It said it was working to ensure there were no more drivers' walkouts, but it still has a mandate to strike.

The BBC understands further discussions are being held with Aslef this week.