Rail passengers may face long queues when buying tickets at train stations from Tuesday, since more than half of providers have said they will not have updated their ticket machines to recognise the new £1 coin by the time it comes into circulation.
The 12-sided coin – which is intended to be harder to counterfeit – was announced in the 2014 budget and will become legal tender on March 28.
Yet 11 out of the UK's 18 rail providers have admitted some of their ticket machines will not be updated in time for the change, according to a survey by The Telegraph.
Major providers including Southern Rail, Virgin East Coast and Transport for London said their machines would not be ready by Tuesday, prompting concerns that travel chaos could ensue.
James Daley, director of consumer rights campaign group Fairer Finance, said the failure was another demonstration of the companies' lack of consideration for their passengers.
He told The Telegraph: “Most of these companies effectively run monopolies which means there is no competitive pressure to act quickly in their customers' interest.
“It is yet another example of them not prioritising customers' needs and proves that the market is failing them."
A spokesman for Virgin East Coast said it was working on updating its machines, but said in the meantime customers could exchange their new pound coins for the old ones with staff.
Meanwhile, Greater Anglia, C2C Rail, Virgin West Coast, Heathrow Express, have said all their machines will accept the new coin.
It recently emerged that the new £1 coin could pose problems for drivers, with an estimated one in ten parking meters not ready.
Vending machine operators are also not prepared. Despite a £32m industry effort to upgrade Britain's 500,000 vending machines, 15 per cent of them still unable to accept the new coins.
Shops have been told to stop accepting the old coins by 15 October, prompting money experts to warn of further chaos across a number of sectors later this year.
The Government estimates around a third of the £1.3 billion worth of coins stored in piggy banks or savings jars around the UK are denominated in the current £1 coins.