Crunch talks to seal Crossrail deal within days

The gathering comes after Gordon Brown indicated the go-ahead for the rail link could be signed and sealed within days - if the business community comes up with the cash.

The Prime Minister pre-empted his own spending review by announcing the Government had found the money.

Now the business community needed to make a "significant contribution" to the £16 billion cost, he said in a speech to the City. "No government has previously managed to bring together the financing necessary. In the last few months we have worked day and night to achieve this."

He added: "This is a huge national project that is vital for long-term prosperity of the nation's capital and indeed the whole country. And I can say today that if others are prepared to play their part, the necessary funding from the Government will be provided in the forthcoming Comprehensive Spending Review - funding only possible because we have kept public spending in other areas under control."

London has waited more than 20 years for the line, which will run from Heathrow to Canary Wharf and beyond via the West End and the City.

Mr Brown made clear that the only remaining snag was the level of business funding. "A comprehensive package is needed to fund the £16 billion required - largely from the public sector but also including the proceeds from a supplementary business rate and additional contributions from certain London businesses and developers who will benefit significantly from Crossrail."

One government insider said the scheme was effectively "in the bag".

The Evening Standard revealed last week that negotiations had stalled amid recriminations over how much the business community in the City should pay towards the scheme, which could be up and running by 2016.

BaronessValentine, chief executive of business group London First, said: "The champagne stays on ice ... [but] we are hopeful that a positive announcement might be just around the corner."