Calls for workers to be found new jobs when an on-board trolley service on Southern trains ends this weekend have grown after claims that the decision to end the contract was taken months ago.

Southern, which runs commuter and other services through parts of Bromley and Lewisham from London to the Sussex coast, said most passengers bought food and drink at stations, so the trolley service will end on Sunday, when Southern joins the Govia Thameslink Railway franchise.

The Rail, Maritime and Transport union (RMT) claimed that Rail Gourmet, which operates the service, was told three months ago that the contract would end this weekend.

The union said the 70 workers involved were only told in the past few days that they are losing their jobs.

RMT general secretary Mick Cash said: "It is scandalous that Rail Gourmet were apparently told back in April that they were losing the Southern trolley contract and yet chose to keep that information from the unions and the workforce and instead sacked them at four days notice.

"This disgraceful move is an attack on both our low paid members and the services that they provide to the travelling public and has been handled in the most shocking fashion.

"The fact that is all bound up in the franchising process speaks volumes about how rail privatisation impacts on staff and passengers alike in the drive for profits.

"RMT believes that both Rail Gourmet and Southern now have a clear duty to find these staff suitable alternative employment."

A Southern spokesman said: "The popularity of station coffee shops and food outlets has steadily increased as we have invested in and developed our stations over the past few years with the majority of passengers opting to purchase food and drinks before they board their train.

"The number of customers who want to use the on-board trolley service tells us that this is no longer our customers' preferred service and so our current on-board trolley service will end on July 26 when Southern Railway joins the Govia Thameslink Railway franchise.

"We are working with Rail Gourmet to explore the possibility of helping any of their staff find employment with us going forward."

Southern stressed that the workers involved were employed by Rail Gourmet.

A Southern spokesman said: "We are working with Rail Gourmet to help their staff find employment with us and we are prioritising their displaced staff in our application process."

A Rail Gourmet statement said: "Rail Gourmet can confirm that its contract with Southern Railway has come to an end early and at short notice as a result of Southern joining the Govia Thameslink Railway franchise.

"As a result, discussions with Rail Gourmet employees who have been affected by this decision have already started, and we are working hard to find alternative employment for them elsewhere in the company and with Southern Railway.

"Rail Gourmet received formal notice of the termination of the contract on Monday 20 July 2015."