London saw nearly 450,000 extra visitors in the three-month period compared to the same period in 2010, representing a year on year gain of 12.6%.
The rise is being attributed to one-off major events in the capital, including the Royal Wedding in April and the UEFA Champions League Final at Wembley Stadium in May.
The survey shows that leisure visits were the biggest growth driver, with 2.2 million visits representing an increase of 14.1%.
Business visitors followed closely with an increase of 13.7%, and just under 770,000 visits.
The report shows that visits from London’s biggest in-bound market, North America, were up by 8.6% and visitors from Europe up by 10.4%.
Mayor of London Boris Johnson said that the "growing buzz" of the Olympic Games meant it was "little wonder that London continues to dominate as one of the most desirable destinations in the world."
He added: "2012 is set to be a huge year for the capital and we stand ready to welcome the world."
The IPS interviews more than a quarter of a million travellers each year at all major airports, sea routes and Eurostar terminals.
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