London Transport announced a 4.5% average rise, one per cent above inflation, but the hike was criticised by commuter groups who say London's tube system is already the most expensive in the world.

Cynthia Hay, of Capital Transport, said: "Passengers have been betrayed. Not only have many fares increased by more than the promised one per cent above inflation but the service they get in return is deteriorating."

Some single fares will rise by as much as 12.5%, with the cheapest single fare rising from 80p to 90p.

London Transport's Market Planning Chief, Adam Goulcher, said: "We have, as always, tried to achieve a balance between keeping fares affordable and providing sufficient extra revenue to fund improvements to the service."

He added that LT was offering extra savings on the carnet book of tickets and a reduction in some child fares.

The Shadow Minister for London, Richard Ottaway, blamed the fare rises on Labour's "failure to fully embrace the private sector".

He said: "They are muddling along with a public-private partnership. It is proving fiendishly complicated to draw up the private sector contracts and there is no evidence that the public sector will be able to run the underground any better than now."

The news came as the RMT threatened three separate strikes on sections of the underground.

Season tickets up

An annual season ticket for all six underground zones will be going up 2.6% to �1,396. But an annual season covering just Zone One rises 10% to �572.

A weekend travelcard ticket for Zones One and Two will rise 9.6% from �5.20 to �5.70, and some weekly Travelcards will go up 10%.

The new fares are being introduced on 3 January, 1999, and will bring in an extra �58m in revenue.

Unlike commuter main line passengers, Tube travellers do not get the compensation of having their fares pegged back if performance is poor.

Fares on most south-east rail services will rise by less than inflation, it was announced in early October.

However, underground passengers can make refund voucher claims if they are delayed for more than 15 minutes on any journey.

On the buses, a single bus fare from Victoria to Aldwych in central London will go up 11.1% from 90p to �1.