The COI has put out a £184,000 brief on behalf of London & Partners, which the Mayor of London set up on 1 April.
The new body will act as a single promotional agency for the capital as a place for tourism, inward investment and study.
Briefing documents leaked to PRWeek explain that the appointed agency will support the 'Limited Edition London' campaign during 2011 and into 2012 and will create a strategy including a calendar of events - including a major launch event in July - to drive visitors in the run-up to the 2012 Games.
The briefing documents also reveal concerns about tourism numbers dropping during the Olympics: 'There is a very real threat to tourism caused by displacement, ie visitors actively staying away because of London's host city status.
'This phenomenon has been recognised in all host cities of large sporting events and there is a potential to lose around 50 per cent of overnight visitors to the capital.'
The campaign activity will be split across the US, the UK, France, Germany, Spain and Italy. London & Partners will also be active in Australia and the growth markets of China and India.
The agency will start work next month and finish in July 2012. The COI is seeking agencies with an understanding of live events and experience of multi-market activity.
London & Partners incorporates the existing Visit London, Study London - which promotes London's 42 universities - and Think London, the city's foreign direct investment agency.
In 2009, Visit London brought in Pitch PR to assist Events For London, charged with attracting, developing and staging major sporting and cultural events in the city.