Drivers on Southern Railway have rejected a deal aimed at resolving a long-running dispute over driver-only trains.

The Aslef union and Govia Thameslink Railway, the owner of Southern, held lengthy talks in a bid to resolve a long-running row which sparked a series of strikes.

The proposed resolution to the dispute was rejected by 54.1 per cent in a turnout of 72 per cent.

Aslef general secretary Mick Whelan said: "We understand and support the decision arrived at democratically by our members and will now work to deliver a resolution in line with their expectations."

The decision has sparked fears of a fresh outbreak of strikes. Thousands of passengers across Sussex have suffered months of disruption because of industrial action and staff shortages.

The Rail, Maritime and Transport union is still in dispute with Southern over changes to the role of conductors and is planning a one day strike on Wednesday.

Govia chief operating officer Nick Brown said: "Naturally we’re saddened and hugely disappointed, as will be our passengers, with today’s decision by drivers, particularly as the agreement carried the full support and recommendation of the Aslef leadership.

"We now need to understand the issues which led to this outcome and we’ll be seeking to meet with the union as soon as possible to see how we can agree a way forward.”

Caroline Lucas, the Green MP for Brighton Pavilion and co-leader of the Green Party, said the Government must now step-in as the dispute threatens to rumble on.

She said: “It’s no surprise that the drivers have rejected this proposed deal as the offer didn’t include maintaining the presence of a guard on every train, which is key to safety.

"It’s now time for the Government to step in and bring this line into public hands.

"Southern are running our service into the ground – and passengers deserve much better than warm words from ministers who have utterly failed to get a grip on the rail crisis.”

The RMT attacked the proposed agreement worked out between Aslef's leaders and the company, describing it as a "shocking betrayal" of workers and passengers.

Aslef's leaders said the deal had been misunderstood, insisting it would lead to safety improvements.

The two unions have been in dispute with Southern for almost a year over staffing issues, including whether a second, safety critical member of staff should be guaranteed on trains.

A series of strikes have been held, causing chaos for Southern's 300,000 passengers, who now face the prospect of further disruption.

RMT leader Mick Cash said: "This ballot was entirely a matter for Aslef and their Southern members. RMT has remained focused on the industrial and public campaign to protect the safety of the travelling public and to put access and safe operation before profits.

"RMT will now look to take that campaign into its next phase working with our sister rail unions, the wider trade union movement and the passengers who use the railway.

"RMT repeats the call to Southern to give the guarantee of a second, safety critical member of staff on their trains and to sit down with the unions in new talks around the issue of safe train despatch."

Paul Plummer, chief executive of the Rail Delivery Group, which represents train operators and Network Rail, said: "This is a disappointing outcome that will worry hundreds of thousands of passengers.

"At the heart of this dispute are changes that will provide passengers with the better service they need and want.

"Where safety, jobs and pay are unaffected, the railway must be able to harness new technology and smarter ways of working to deliver the modern rail service the country needs."