Converting online train journey planners to greyscale as a mark of respect following the Duke of Edinburgh’s death has led to complaints from passengers and rail staff that they are now difficult to read.

The decision by National Rail Enquiries (NRE) and individual train companies to remove colours from their websites goes beyond Government guidance for the period of national mourning, which only suggests organisations use “black edging or black banners”.

NRE’s Twitter account received a barrage of angry messages following the change.

Users described the decision as “utterly ridiculous”, and claimed it has made train timetables “extremely difficult to read”.

Others claimed the switch is in breach of disability discrimination laws.

In response to a passenger asking if there was a way for users to change the website back to normal, an NRE employee wrote: “Unfortunately, I do not believe there is currently”, adding: “I too have been struggling to read while it is coloured differently.”

Elisabeth Ward, accessibility specialist at disability equality charity Scope, said: “While it’s important to pay respects when tragic events happen, it’s vital this doesn’t stop disabled people from accessing essential services.

“Accessibility always matters, even in a period of national mourning.

“This decision to change entire websites to greyscale did not consider disabled people’s access needs. It’s another example of disabled people being forgotten.

“Not only does it cause problems for those who need sufficient colour contrast, but it also interferes with tools and plugins many disabled people use to help make websites accessible.”

She added that public sector organisations “have a legal duty to make sure nobody is being blocked from using vital services and information”.

Mick Cash, general secretary of the Rail, Maritime and Transport (RMT) union, said: “Whoever has made this decision has little or no consideration for the accessibility of disabled passengers and workers.

“It is vital that the rail industry reverts back to their original website configurations immediately.

“It is possible to mourn for Prince Philip without making life even more difficult for disabled people and workers to use our railways.”

Industry body the Rail Delivery Group, which runs NRE, issued a statement on Monday which said: “The National Rail Enquiries website has been temporarily greyscaled as a mark of respect following the death of HRH Duke of Edinburgh on Friday.

“We are listening to feedback about how people are using the website and are making further changes today to make it more accessible to all our customers.”

The www.nationalrail.co.uk website reverted to its usual colours at 10am on Monday, the Rail Delivery Group said.