A 1.1 per cent rail fare increase has come into effect across England, Scotland and Wales, according to the Rail Delivery Group (RDG).
The increase is the smallest hike since 2010 and will only apply to unregulated fares, such as off-peak leisure tickets.
Increases in regulated fares, including season tickets, is capped at one percent, July's retail price index inflation rate.
While the increase is lower than any rise over the last five years, research published in August showed that the cost of train travel has risen nearly three times faster than wages over the past five years.
Regulated ticket prices increased by 25 per cent between 2010 and 2015, while average pay rose nine per cent during this period, according to a study by the union TUC.
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Bruce Williamson, of campaign group Railfuture, said: "High street prices have remained stagnant for more than a year, with the official consumer price index inflation figure hovering around zero, yet the government thinks it's fair to make rail travel even more expensive."
For every pound sent on rail fares, 97 pence will be spent on trains, staff and other running costs, after the sharp rise in passenger numbers over the last 20 years resulted in higher operating costs, leaving three per cent for profits.