Plans to scrap one-day Travelcards will make train trips to London more expensive, a campaign group is warning.

The paper tickets – which allow passengers unlimited travel on the capital’s tubes, trains and buses – are being phased out from January by mayor Sadiq Khan.

But Campaign for Better Transport says the daily tickets make it ‘simple and affordable’ for people to travel to and around London and without them public transport will immediately become more pricey.

Currently, people going into London by train can add a Travelcard onto their national rail ticket to use on Transport for London services, meaning they buy one ticket for their trip.

But from next year passengers will buy their train ticket for their journey in and out of London and then be required to use a contactless bank card or oyster card for their travel within the capital when they get there.

Yet the move to switch from one integrated ticket, to a ‘pay as you go’ system will make it more difficult to access child and other discounted fares, says the group, and push up the cost of a trip by as much as 16%.

On average, off-peak travel may cost between £1 and £3 more if all TfL journeys, once in the capital, take place between zones 1 and 2.

But this could rise to between anything from £3 and £10 if travel within London stretches out to zone 6.

Norman Baker, from Campaign for Better Transport, said: “At a time when we should be doing all we can to encourage people to use green public transport to access London’s shops and attractions, this move is going in entirely the wrong direction.

“Public transport works best when you can use one ticket for your whole journey, so we need more, not less, integrated ticketing.

“Transport for London must rethink its plans as a matter of urgency and work together with the Department for Transport and the train operating companies to find a way to save the Day Travelcard from extinction.”

Last year more than 14 million day Travelcards were sold.

But City Hall’s decision to scrap the daily cards, rarely used by Londoners, is understood to be driven by pressures to generate more income across its network.

Rail firms however, are said to be concerned by the impending change, which they fear will discourage some passengers from choosing to visit the capital by train, that will ultimately result in a loss of revenue for them.

Analysis by Campaign for Better Transport estimates that a lack of Family Travelcard from January will mean families pay on average 16% more to visit the capital, with some facing even steeper increases depending on where they are travelling from.

And this extra cost will be on top of a need to take out oyster cards in advance for each child in the group, in order to have child discounts added at a London station in person before using the capital’s transport system.

Independent travel watchdog London Travelwatch is also opposing the plans. It fears some travellers, depending on their route, could face paying more than £14 a day for tube and bus travel in London – journeys they are currently charged £5.50 for as part of their Travelcard deal.

On Thursday, Campaign for Better Transport launched its ‘Don’t Cut The Card campaign’ and appealed to rail users to share their views.

Norman Baker added: “The cost implications and added complexity of buying a rail ticket are such that they will discourage many people from travelling altogether and could result in an ‘own goal’ for Transport for London, with a drop in revenue.”