LONDON is officially the most expensive transport capital in the world, new research has shown.

The news comes this week as the Mayor of London Ken Livingstone put into place more cash fare increases on tubes and buses - this time by 33 per cent.

The rise has been called "astronomical" by travel watchdogs.

The research by Liberal Democrat transport spokesman on the London Assembly, Geoff Pope, compared the cost of cash and Oyster card fares for a single tube journey in zone 1 and 2, a day travel card and a zone 1 and 2 monthly travelcard, with seven other European capitals as well as New York, Moscow and Tokyo.

Mr Pope said: "Monthly fares for regular commuters are extortionate - well over twice New York, Paris or Rome.

"The Mayor can get away with it because he knows he has passengers over a barrel. Cash fares are also scandalous: short journeys are cheaper by black cab.

"London is officially the world's most expensive public transport capital. Unfortunately, sky-high tube fares do not mean value for money: Londoners are paying the price for overcrowded and unreliable journeys."

Mr Pope, who is also chairman of the transport committee, added: "With the tube being re-built over the next ten years we are bound to have cancellations and delays. It's time these disruptions were made up for with cheaper tube fares."

Chairman of London TravelWatch Brian Cooke said: "We are extremely concerned about the exorbitant cash fares on buses, which rise by a third, from £1.50 to £2, and on tubes in zone 1 passengers will see a single fare rise to an astronomical £4 - even if they only go one stop."

Mr Cooke said the increases would hit tourists the hardest and drive people away from public transport back to cars and taxis.

"That would be deeply disappointing," he said.

From this week, peak bus fares with Oyster are frozen at £1, which now becomes a single flat Oyster fare throughout the day, but cash users will pay £2 for the same journey - a 50p increase in price.

All Oyster single fares are frozen across London and the Oyster daily price cap for adults remains 50p below the One Day Travelcard price.

The Mayor announced two years ago that bus fares would rise by ten per cent above inflation for three subsequent years to help fund the investment programme on London transport.

Mr Livingstone said: "There are now huge savings to be made by using Oyster. We have been able to freeze many Oyster pay-as-you-go bus and tube fares this year. Many now cost half the same journey paid by cash."

But Mr Cooke said: "The above-inflation price rise on rail fares is more than disappointing and will seem a particularly bitter pill to passengers in the London area, who are increasingly faced with crowded trains and crowded platforms."

The Mayor's transport policies have come increasingly under fire in recent weeks.

Last month deputy chairman of the London Assembly transport committee Roger Evans said the free travel for under 16s on buses should be scrapped.

Writing on his blog site he said: "Given the cost of this concession, the levels of antisocial behaviour and the lack of control over the issuing and checking of passes, I will be recommending abolition - if asked."

Opponents have recommended lowering train fares before 7.30am to ease overcrowding and help "early morning low-paid workers".

Transport for London is urging more people to use Oyster cards to combat the new year rise in fares.