Investment in major infrastructure is essential if London is to retain its competitiveness, a new report says.
The study, by the London School of Economics, found major projects such as the planned Crossrail scheme are vital for retaining London's productivity.
Report authors found that investing in infrastructure would actually help reduce national debt.
They also claimed that public spending in London is low compared to that in other world cities.
Commenting on the report, Mayor of London Boris Johnson said: "I want to remind the government that growth is essential to the health of our public finances.
"Only by continuing to invest in London - the engine room of the national economy - will the nation as a whole be able to grow its way out of trouble.
"The UK cannot afford the cost to the economy if the capital is starved of vital investment in infrastructure projects like Crossrail and the upgrade of the Tube."
The report found that London and the south-east of England contributes 43% of the nation's taxes.
It also said London has produced more in tax than it consumed in public revenue in every year but one since 1989.