The Lib Dems believe Tube and bus travel should be priced the same way
Campaigners are calling for one-hour tickets to be introduced on London's buses to make journeys easier.
A petition has been started by the Liberal Democrats at City Hall who say London's mayor should give people travelling by bus "a fair deal".
The tickets would allow commuters to switch to any number of buses within an hour for the price of one journey.
But a spokesman for mayor Boris Johnson said the scheme was too "complex and expensive" to introduce.
Currently commuters using Oyster cards pay £1 per bus journey and people using paper tickets pay £2 for a single fare.
Liberal Democrats' London Assembly member Caroline Pidgeon said: "You can already switch from Tube to Tube on the same ticket so it makes real sense to allow people to do the same with buses.
"One hour bus tickets already operate successfully in Paris, Rome and Brussels. It is time London caught up."
But a spokesman for the mayor said the scheme did not have his support.
He said: "This is because it would be an extremely complex and expensive exercise that would only benefit a small number of passengers as the majority of bus users in London pay for journeys using pre-paid season tickets or concessionary passes."