Southern Railway workers are to stage 14 days of strike action in five blocks from next month in the long running dispute over the role of conductors.

The Rail, Maritime and Transport union announced an escalation of industrial action which will bring fresh travel chaos for hundreds of thousands of passengers.

The strikes will start on October 11 and will be held intermittently until December 8.

The union has held a series of walkouts in recent months in protest against changes to the role of conductors at Southern, which is owned by Govia Thameslink Railway.

Conductors are to take strike action by not booking on for any shifts between:

• 00.01 on Tuesday 11th October and 23.59 on Thursday 13th October

• 00.01 on Tuesday 18th October and 23.59 on Thursday 20st October

• 00.01 on Thursday 3rd November and 23.59 on Saturday 5th November

• 00.01 on Tuesday 22nd November and 23.59 on Wednesday 23rd November

• 00.01 on Tuesday 6th December and 23.59 on Thursday 8th December.

RMT General Secretary Mick Cash said in a statement: "Yet again our members are being forced to take industrial action in a bid to maintain a safe and secure service on Southern.

"Govia Thameslink and the government have made it clear that they have no interest in resolving this dispute.

"Instead they have begun the process of bulldozing through the drive towards wholesale Driver Only Operation (DOO) without agreement and without any concern for the impact on safety, security and disability access.

"Last week there was a train derailment near Watford that involved two trains.

"The guards on both trains played a vital role in protecting the passengers and the trains in what were extremely frightening circumstances.

"If the train had been DOO and without a guard the consequences would have been far worse.

"This week we reached a deal with Scotrail that we are recommending for acceptance in a referendum of our members, that guarantees a fully competent conductor/guard on every new train.

"This agreement protects passengers, and guarantees a second safety trained member of staff on board a train, who can assist if there is an incident such as we recently saw near Watford. 

"If an agreement can be reached on Scotrail, then an agreement can also be made on Southern.

"In the light of these recent developments it is disgraceful that neither the company or the Government are prepared to engage and are continuing to attempt to impose DOO in the interests of putting profit before safety.

"We call on them to get round the negotiating table as an urgent priority."

GTR’s Passenger Services Director Angie Doll said in a statement: "The RMT’s desire to heap yet further travel misery on the public and affect the everyday lives of so many people is shameful.   

"A comprehensive and fair offer has been on the table for weeks and the union leadership’s claims about jobs, pay, safety are trumped-up make believe.  

"This scaremongering by the RMT union is a contrived attempt to gain public support when it knows its spurious arguments about jobs, pay, accessibility and safety have been demolished by independent experts and analysis and are falling on deaf ears.

"As a responsible operator, our priority is to make our services more accessible, not less, and we will not be shaken in that commitment.  

"We care deeply about those of our customers who are less mobile and help thousands of elderly and disabled customers week in, week out, to travel with us.  

"We will do everything we can to ensure those needing help getting on and off our trains receive our care and attention to get them where they want to be, promptly and hassle-free.

"We’ve always said we are ready, willing and able to sit down and discuss how best we implement our modernisation plans and give our customers the services they expect and deserve.  

"The RMT has to stop being the problem and get on board  - finally - and be part of the solution.  Everyone is sick and tired of the union’s posturing and it has to stop, and stop now. It’s what the public want."

Anthony Smith, chief executive of the independent watchdog Transport Focus, said: "As ever, it is passengers that suffer in the event of strikes. We are disappointed that the two parties have still not resolved their differences.

"They need to get back round the table and bring services back to normal as soon as possible."

The watchdog is appealing for passengers using Southern or the wider Thameslink network to download its app and share their stories.

Passenger manager Linda McCord said: "We use the stories we hear to add a real sense of the human impact of performance issues. We share them with the operator to suggest ways to win back some passenger trust."

Transport Focus said it wants to see the railway get back to business as usual as soon as possible, but in the meantime it suggested a one-off gesture to recognise the "extreme problems" faced by passengers, such as improved compensation as well as a fares freeze for season ticket renewals.