Heathrow Airport welcomed 5.27 million passengers in February.
This represents a 1.7 per cent rise on the same month in 2016, which included a leap day.
Heathrow, the UK’s busiest airport, said the growth was due to the use of larger, fuller aircraft.
The west London hub’s chief executive, John Holland-Kaye, said: “Heathrow is off to a flying start in 2017. We’re delivering the best service of any major airport in Europe to record numbers of passengers and boosting British exports with record cargo volumes.”
Last month, the British government published a consultation on its draft national policy statement which sets out why a third runway at Heathrow is its preferred option for boosting airport capacity in south-east England.
Gatwick Airport, which made a rival bid to build a new runway, saw a 9.9 per cent year-on-year increase in passengers in February to three million.
The West Sussex airport’s long-haul routes continued to grow, up 20.3 per cent.
Los Angeles was up 90 per cent on the same month last year, and passengers will soon have another option for travel to the USA's west coast with British Airways starting its new route to Oakland, California.
Gatwick chief executive Stewart Wingate said: “Gatwick’s February passenger figures demonstrate the confidence we are witnessing from our passengers, with travel still high priority following the Brexit referendum.”
He added that a 6 per cent increase in cargo demonstrates the airport’s “vital economic role within Britain and internationally” as it continues to offer the Government a “credible and deliverable option” for runway expansion.
Manchester Airport maintained its recent spell of double-digit growth with an 11.1 per cent rise in passengers in February, reaching 1.66 million.
Charlie Cornish, chief executive of Manchester Airports Group, which owns the airport, claimed the figures demonstrate the need for the government to improve transport links across the North.
He said: “Manchester Airport is continuing to show its importance in providing global connectivity to a wider and wider segment of the country.
“No other airport outside of London can come close to offering the range of global destinations that we offer from our two runways.
“Now is the time for government to start making concrete plans to improve access to the airport for the whole of the North.
“Businesses to the east and the west, particularly in key northern cities such as Liverpool, Leeds, Bradford and Hull, would benefit from more rapid and convenient rail links to a globally connected airport.”