Visit London is part funded from the London Development Agency (LDA), by around £11.7m a year as part of the body’s Global Competitiveness programme.
However, the LDA is set to lose funding from government for all but projects that it is legally committed to – a step further than original plans to merge it into the Greater London Authority.
A Mayor of London spokesman said: "We were given assurances by the Treasury that an appropriate pot of money would be available for London and we plan to fight this all the way. These are priorities that the government has asked us to deliver and that Londoners expect. We are determined to deliver them for the economic benefit of the city and to prepare London for the 2012 Games."
Visit London is now waiting for further clarification of how the funding cuts will impact on its work, which is also boosted by partnerships with businesses in the conferences and events industry, such as Eurostar, Radisson Edwardian hotels, Wembley Stadium and the O2 arena.
Business and major events PR manager Chloe Couchman said: "As we approach the 2012 Olympic and Paralympic Games it is more important than ever that we continue to promote the capital as a tourism and business destination. The tourism industry is worth around £16bn to London's economy and supports almost 300,000 jobs. We believe that international promotion of the capital must remain to ensure London's future as a world class destination."
As part of the government’s comprehensive spending review on 20 October, Visit Britain learned it would lose 34% of its budget.