The Overland train service connecting Melbourne and Adelaide for more than 130 years has been guaranteed to the end of March after being thrown a lifeline by the Andrews government.

But the route's future beyond that remains unclear amid dwindling passenger numbers and a long-running funding dispute between the Victorian and South Australian governments.

The Overland train has been guaranteed until the end of March.

The Andrews government announced on Friday it would help the operator, Journey Beyond Rail, keep the service running for the next three months "to give holidaymakers certainty".

"Given the South Australian Liberal government's cut to the service, Victoria will use the next three months to continue discussions with Journey Beyond about the future of the Overland," a spokeswoman said.