Passengers using Heathrow fell by 2.2% to 6.6 million in April over the same month last year.

Numbers fell on routes to North America, the Middle East, Asia-Pacific and Latin America.

However, the airport pointed out that underlying passenger growth was 1.4% when combined with figures for March.

This meant that more than 13 million passengers travelled through the London hub for the first time in March and April.

Domestic and emerging markets contributed the strongest passenger growth largely due to airlines flying larger, fuller aircraft to destinations in the UK, South Asia and Africa.

The April figures gave the airport an annual rolling total of 78.3 million passengers.

Heathrow chief executive John Holland-Kaye said: “We’re seeing more passengers and trade flow through Heathrow than ever before.

“A third runway is a tremendous opportunity to grab a greater share of this global growth for Britain and we’re counting on our politicians to seize it with a ‘yes’ vote on Heathrow expansion this summer.”