Spanish-owned airport operator BAA reported a 4.1% decline in passenger traffic at its five UK airports to 9.6m during July 2012, with fewer Brits flying abroad.
BAA chief executive Colin Matthews said: "The drop was more pronounced in the second-half of the month and it is likely that the Olympics played a part, with UK passengers staying at home, as well as non-Olympic visitors from overseas choosing to defer their journeys,"
During the period, passenger traffic at Heathrow airport declined 4.4% to 6.6 million when compared to the same month in 2011.
Domestic passenger traffic at Heathrow rose 1.2%, while European scheduled traffic declined 6.6%.
Heathrow's North Atlantic traffic remained almost unaffected reporting a rise of 0.1%, while other long-haul routes registered an accumulated decline of 6.3%.
Indian to-and-fro passenger numbers at Heathrow decreased 11%, while Brazil and China reported respective rises of 15% and 3.4%.
Passenger traffic at Stansted and Glasgow airports declined 5.3% and 0.5%, with Southampton recording a 9.5% rise during July, compared to the corresponding month in 2011.
During July, Aberdeen's passenger traffic rose by 4.4% when compared to last year, reporting a combined rise of 0.9% across all Scottish airports.
BAA-operated airports reported a 0.6% rise in cargo volume in July 2012.
Image: Heathrow's European scheduled traffic during the period declined 6.6% during July 2012. Photo: courtesy of Warren Rohner.