Rail passengers travelling on the first working day of 2018 are being hit with the largest fare rise in five years.

Average ticket prices across Britain went up by 3.4% on Tuesday.

Protests are planned at around 40 railway stations to mark the biggest increase since 2013.

Members of the Rail, Maritime and Transport union will hand out chocolates to passengers in a bid to "sweeten the bitter pill" of the price increase.

Many season tickets have gone up by more than £100, including in Theresa May's constituency of Maidenhead, where an annual pass to London rose by £104 to £3,092.

Other commuter routes that are now more expensive include Elgin to Inverness, which is up £100 to £2,904.

Stephen Joseph, chief executive of the Campaign for Better Transport (CBT), accused the Government of choosing to "snub rail passengers".

Mr Joseph said: "The extra money that season ticket holders will have to fork out this year is almost as much as drivers will save.

"That doesn't seem fair to us or the millions of people who commute by train, especially as wages continue to stagnate. What's good enough for motorists should be good enough for rail passengers."

The Government uses the previous July's Retail Prices Index (RPI) measure of inflation to determine increases in regulated fares - 3.6% in 2017.

These are around half of all tickets and include season tickets on most commuter routes and some off-peak return tickets on long-distance journeys.

Bruce Williamson, of campaign group Railfuture, warned that "people are being priced out of getting to work".

He called for the Consumer Price Index (CPI) inflation measure to be used for regulated fare increases.

Mr Williamson said: "If CPI had been used instead of RPI since 2004, then rail fares would be 17% lower, a significant amount of money for season ticket holders who are spending thousands of pounds to get to work.

"It's no wonder that poor value for money is the number one concern of rail travellers, with British rail fares amongst the most expensive in Europe."

A Department for Transport spokesman said: "We are investing in the biggest modernisation of our railways since the Victorian times to improve services for passengers.

"We keep fare prices under constant review and the price rises for this year are capped in line with inflation, with 97p out of every £1 paid going back into the railway."