Tens of thousands of commuters could be faced with further travel woes as the RMT Union ballots more than 1,000 staff of Govia Thameslink Railways (GTR) for strike action in a row over pay, jobs and safety. The move is the latest development in the dispute between the union and GTR, which operates Southern Rail, Thameslink and Gatwick Express services.

RMT officials said they rejected the latest offer from GTR because it would apparently lead to cuts in pay and result in a "massive" increase in lone working. The union will now begin a ballot for both strike and action short of a strike, with papers going out on Tuesday 2 August and the ballot closing on Tuesday 16 August.

"The basket-case Govia Thamelink franchise are at it again," said Mick Cash, the general secretary of the RMT.

"Not content with axing catering services, closing ticket offices and attacking the role of their guards they now want to threaten 130 station jobs and compromise the safety of both their passengers and staff alike.

"These plans fly in the face of the response from the thousands of passengers who objected to the closure of ticket offices and the de-staffing of stations as Govia drives on with plans for a "faceless railway" where the public are left to fend for themselves on rammed-out, dangerous and unreliable services."

Cash said his union remains available for "serious and meaningful" talks, while GTR said it was "disappointed" by the RMT's latest call for industrial action. It argued its plans would "improve passenger experience" and said staff affected by the reforms have been offered a pay rise.

"The RMT's threat of further industrial action is entirely unwarranted and clearly another bid by the union to disrupt passengers and GTR across as many parts of our franchise as possible," said Keith Jipps, passenger service director at GTR.

"We have listened to passengers and modified our proposals, addressing the concerns of both London TravelWatch and Transport Focus.

"Our new Station Hosts will be paid more, be able to work in safety and provide passengers with better customer service, but the RMT is not concerned with improving the experience for passengers and are dismissing significant improvements to the terms and conditions for staff."

What GTR is promising

· All affected staff will receive an uplift in salary or an additional allowance, and the working week will be reduced from 39 hours to 35 hours for some
· There is a job for everyone – no compulsory redundancies
· Assurances have been given that safeguard staff security
· All modernised stations will be staffed from the very first train to the very last, seven days a week – in total an extra 2,600 hours per week
· Station facilities, like waiting rooms and toilets, will be open for longer
· The stations will continue to sell the full range of tickets currently on sale at ticket offices
· GTR will introduce Oyster 'pay as you go' style smartcard ticketing across the network which can be topped up at home and guarantees the cheapest walk-up fare for the day
· Queuing standards will be maintained
· GTR is talking with disability user groups to ensure its plans not only meet but improve the station experience for people with disabilities