Bid hangs on £1bn Tube

London's struggling Olympic bid would be revitalised if a delayed £1billion Tube line extension is quickly approved, transport experts and senior politicians said today.

Pressure was growing on Transport Secretary Alistair Darling to give an urgent go-ahead to the East London line extension after strong criticism of the capital's transport infrastructure from Olympics chiefs.

The International Olympic Committee this week put London on the shortlist of five cities bidding to host the 2012 Games - but warned it had no chance of victory against Paris or Madrid unless rapid improvements were secured to the creaking and overcrowded Tube.

Although the Government officially backs the bid to host the Games, criticism has emphasised the need to improve the package of transport measures that will definitely be in place by 2012.

The East London line extension has backing in principle but is in a desperate battle against other national rail schemes to be awarded public money to make it happen.

Campaigners now see it as the only way to convince the IOC that both London and the Government are serious about hosting the Games - and say construction work must start before July next year, when the Olympic host city is chosen.

The extension would take the line to Highbury and Islington in the north and three stations in the south - Crystal Palace, Clapham Junction and West Croydon. This would allow direct connections with the Victoria line, North London line - which goes to the proposed Olympic village in Stratford - and suburban rail services in south London.

The project has the advantage of being relatively cheap to build - while dramatically improving the transport options of the expected 500,000-a-day spectators.

Many travelling from east and south-east London would not have to travel into the centre to change trains, while spectators flying to Gatwick would need only one connecting service to reach Stratford.

Crucially, the extension could be finished several years in advance of the opening ceremony, unlike the eastwest Crossrail service, another delayed project. This would have linked Heathrow direct to Stratford but is now unlikely to be finished by 2013, at an estimated £10 billion cost.

Ken Livingstone and his Conservative rival for Mayor Steve Norris joined forces last night to call on Mr Darling to find the money needed.

Mr Livingstone said: "If they want to win the Olympics they have got to invest in transport."

Mr Norris said: "Not to do the East London line has been criminally negligent. If the IOC is a spur to getting it started, so much the better."

The IOC's criticism has also prompted East London line campaigners to write to London's new bid chairman, Lord Coe. Archie Galloway-chair of the East London Line Group, which includes 13 borough councils and major organisations such as Canary Wharf Ltd, London City Airport and London First, said the scheme could help rescue the Olympic bid. Mr Galloway said: "Crossrail is impossible to have done in that time. But the East London line would not only be ready, it would be tried and tested.

"If they don't do the East London line I think it will kill the bid."