Only a few successful agencies made it through the long selection process to the official meetings at 2012's offices in Canary Wharf, but then discovered that they would need to become a tier-three sponsor at a cost of nearly £10m if they wanted to develop the London 2012 official ad campaign.

Following this revelation two major advertising groups have told The Sunday Telegraph that they are now not interested in pitching for the account, although they refused to be named.

The winning agency is unlikely to have to pay an up-front fee but it will have to agree to do millions of pounds of work in exchange for being named as an official sponsor of the games.

A spokesman for 2012 confirmed that it was looking at getting a marketing services partner "on board" as a tier-three sponsor. He added that other sponsors had made "value in kind" deals including chewing gum brand Trident, technology group Airwave, Boston Consulting Group and solicitors Freshfields.

Some ad industry sources claim that the marketing benefits of having an agency associated with the Olympics are limited and not sufficient enough to justify the financial commitment.