The South Australian Government has secured a commitment from Great Southern Rail to base more staff in Adelaide, as part of a $1 million deal.

The money will be spent over three years and is a renewal of the State Government's funding commitment for The Overland passenger service, which runs twice a week between Adelaide and Melbourne.

Concerns had been raised about the future of the service, which has not released its timetables for next year.

The Victorian Government is still in negotiations with Great Southern Rail over its portion of funding for the service.

Great Southern Rail chief executive Chris Tallent said the company was reliant on both states for the service and could not release its 2016 timetable until agreement with Victoria was reached.

"We are delighted the South Australian Government has today committed to a three-year agreement to support The Overland service between Adelaide and Melbourne," he said.

"We are continuing our discussions with the Victorian Government and are hopeful of a positive outcome in coming weeks that will allow the business to open up sales for The Overland for 2016 and beyond."

The South Australian deal will draw 10 to 15 key roles to Adelaide in maintenance, IT, finance, and human resources.

The company has also committed to spending $100,000 a year on promoting South Australia as a tourism destination.

Transport Minister Stephen Mullighan said the South Australian funding would help the service continue.

"This is a very popular tourism service that's important for both South Australia and Victoria," he said.

The deal will not help return war veteran and pensioner concessions, which were cut when the Federal Government withdrew its funding.

Mr Mullighan said the government could not afford to subsidise the concessions.

"That's something that's beyond not just the State Government but the Victorian Government," he said.

"What we now need to see is the Commonwealth come back around the table, reverse these cuts, reverse the cuts they're imposing on our war veterans so they can take advantage of what is a much-loved service here in Australia."