The Department for Transport says cost pressures mean it will review whether the current wi-fi service "delivers the best possible value for money".

But one rail expert criticised the move and said trains could lose custom as a result.

Most operators currently offer free wi-fi as standard on their services.

Transport officials cited a report from independent passenger watchdog Transport Focus, which they said showed passengers were more concerned about value for money, reliability and punctuality than access to wi-fi.

"Our railways are currently not financially sustainable, and it is unfair to continue asking taxpayers to foot the bill, which is why reform of all aspects of the railways is essential," the Department for Transport (DfT) said.

"Passenger surveys consistently show that on-train wi-fi is low on their list of priorities, so it is only right we work with operators to review whether the current service delivers the best possible value for money."

On-train wi-fi equipment installed in 2015 is now in need of replacing and the government said many people on short journeys did not connect to the on-train wi-fi, and used their mobile phone network instead.

However, Anthony Smith, chief executive of Transport Focus, said access to wi-fi was something many passengers now expect as standard.

"Given the post-pandemic need to get more passengers back on the train it would be difficult to justify removing something that makes rail more attractive to customers."

Christian Wolmar, whose podcast Calling All Stations first reported the DfT's move, said passengers needed the reliability of a train's wi-fi, especially on longer journeys.

"People expect to be able to use wi-fi on a train in the same way they would use a toilet," he told the BBC.

Mr Wolmar said the equipment would still have to be replaced for staff purposes, so any savings would be a "relatively trivial amount".

Ultimately, he said the railways would suffer: "I think the operators will lose customers over this, using a train is a marginal thing anyway for many people."

Mr Wolmar said train operators had received a letter from the DfT informing them of the decision to pull funding unless they could make a good business case for keeping it.

He said he expected most services to lose access to wi-fi "over the next year or two".

Andy Bagnall, chief executive of Rail Partners, said the focus should be on "innovating to improve customer experience rather than removing features many passengers value".

"The consideration of this proposal is a symptom of the current disjointed management of industry finances where revenue and cost are looked at separately and operators are unable to innovate in response to customer needs," he said.

The Rail Delivery Group, which represents train operating companies across Britain, declined to comment.