D-DAY for train conductors faced with an ultimatum of taking a pay-off and agreeing to new roles or losing their jobs is looming.

They have until midday tomorrow to accept the offer or Southern Railway has said it will press ahead with the changes, ending conductors' current contracts and offering them all the new role of on-board supervisor.

Southern Railway approached the RMT union to offer staff a lump sum of £2,000 on Monday in return for accepting a new role, which will see drivers take over responsibility for opening and shutting train doors.

The company also renewed other pledges about conditions of work to encourage them to accept the new role, as outlined in an two page advert Southern in today's Argus.

The union refused, accusing the company of proposing a bribe. General secretary Mick Cash said the union would not be "caving into ultimatums that put a £2,000 bounty on members' heads".

But Southern said it was a "final attempt" to resolve the long-running dispute, which has caused travel chaos for months. The company has since began to contact guards directly with the offer, it is understood.

The news came as last night a passenger campaign group was on track to hit its funding target to take the Government to court over the Department for Transport's handling of the Southern crisis. The group has already instructed a lawyer who is asking for documents from its contract with Govia Thameslink Railway - Southern's parent company - to be released under the Freedom of Information Act.

Union bosses claim the new role will be less safe for passengers, and has called a fresh series of strikes from next week. They are pushing for a deal with pushing for the same deal it says the company has given ScotRail, which it says guarantees there will be a second member of staff on all services, trained in safety measures.

The company had refused “point blank” to take part in talks with ACAS - the Advisory, Conciliation and Arbitration Service – in a bid to get negotiations back on track before the next round of strikes, the union said yesterday.

But a Southern spokesman said: "We have made it clear we want to reach agreement with the RMT by Thursday lunchtime on the way we continue to implement our modernisation plans. But as we spelled out in our letter to the RMT, this can now only relate to the detail of our offer. The timescales we are working to and subsequent consequences have been clearly laid out and we therefore hope the union will finally engage with us on this basis to avoid any further unnecessary disruption and distress to our customers and staff.

“Suggesting we do a deal like the one negotiated with Scotrail is nothing but a red herring – we already operate our trains in the way they have agreed for Scotland with drivers opening the doors."