Rail passengers could miss out on discounted fares due to difficulties purchasing the new “millennial railcard”.

The 26-30 railcard, which offers one-third off rail fares for people aged 26 to 30, went on nationwide sale at noon on Wednesday following trials, but some people said they were unable to buy it, despite waiting in an online queue for several hours.

Some passengers were racing to get hold of the railcard before using it to travel on tickets they had already purchased. It is only being sold online or over the phone.

Mark Dryden wrote on Twitter: “What should I do about the queue if I have 26-30 tickets for a 14.33 train from Manchester Victoria to Newcastle?

“Surely it should be easier and quicker to buy the railcard than this or at least be possible to buy them at the station?”

In response to another concerned passenger who asked whether she would be able to claim a refund if she had to pay the full price for a journey on Thursday, the Railcard Twitter account replied: “You need a valid railcard to receive the discount before travelling.”

Alex Turner wrote: “This is ridiculous! I got through the queue after about four hours to find I was only able to select a 16-25 railcard? I have now been kicked out the queue.”

Another Twitter user, Latisha, said she had been waiting for two hours, adding: “Surely the website is designed for the usual traffic you would expect.”

A National Rail spokeswoman said: “We are experiencing high demand for the 26-30 railcard, which is resulting in higher wait times than usual.

“To ensure we give customers a great experience, we have put into place the same type of technology used by other businesses, such as Glastonbury, during high-profile launches.

“When customers access the 26-30 railcard website, they are automatically put into a live queue and are able to sign up to receive email alerts so that they do not have to wait by their computer.

“There isn’t a limited number of railcards being made available, so anyone who isn’t planning to travel today can come back another day to make their 26-30 railcard purchase.”

There have been a number of problems with the new railcard.

The launch of a nationwide trial of 10,000 cards in March 2018 resulted in the railcard selling out on the first day, with people facing website problems for several hours.

Its rollout to general sale was initially due to take place before the end of last year, but this was pushed back to Wednesday.

The delay meant people born on 1 or 2 January 1988 were unable to purchase the card before becoming ineligible.

The cards cost £30 each year and save one-third off most fares.

There are no discounts on season tickets and a £12 minimum fare applies to all journeys between 4.30am and 10am, excluding weekends and public holidays.

Cardholders save an average of £125 a year, according to the Rail Delivery Group.

On Wednesday, the transport secretary, Chris Grayling, set out plans that could allow more than 1 million teenagers to benefit from discounted travel later this year.

The new 16-17 railcard will be launched in September, with up to 1.2 million young people guaranteed a 50% discount on rail travel to coincide with the new academic year.