Adverse weather conditions and a series of strikes by French Air Controllers (ATC) resulted in a decline in the number of passengers travelling through London Heathrow Airport in June. Britain's biggest airport said on Monday (11 July) that 6.6m people travelled through Heathrow's five terminals in June, which represented a 1% year-on-year decline.

Heathrow attributed the slight decline in traffic to the ongoing industrial action in France, which has seen ATC personnel strike 13 times in the last 14 weeks.

However, the impact of strikes in France and of poor weather was partly offset by an increase in the number of passengers travelling to destinations in emerging markets. Heathrow said passengers flying to East Asia and Latin America grew 2% and 3% respectively, while flights to Singapore, Thailand and Korea, China and Mexico saw passenger growth jumping 7% year-on-year.

Meanwhile, cargo volumes at the UK's largest port grew 2.1% in June, driven by an 11% growth in flights directed to China, while cargo volumes to and from India and Turkey were up 3.3% and 3% respectively.

Heathrow said the increase in cargo traffic underlined the need for the government to make a decision on the proposed expansion plans, which would see a third runway built at the airport in south-west London.

"With cargo volumes at Heathrow growing, our next prime minister has a real opportunity to secure Britain's legacy as an outward-looking trading nation," said the airport's chief executive John Holland-Kaye.

"Now more than ever, a decision on Heathrow expansion must be at the top of her in-tray."

Given London's ever-growing air traffic, both Heathrow and Gatwick airports have submitted expansion plans to increase their capacity, only for the government to postpone the decision until after the referendum on the European Union.

However, following last month's vote, Holland-Kaye insisted it was time for the government to make a statement of intent by choosing Heathrow's proposal and finally approving it.

"We'll double cargo capacity at the UK's largest port, helping even more British exporters trade with all the growing markets of the world," he said.

"And at a time of uncertainty, a £16bn (€18.7bn, $20.6bn) privately funded infrastructure investment will create jobs and growth across the UK.

"And with parliament overwhelmingly endorsing a third runway, our next prime minister can send the strongest possible signal that Brexit Britain is open for business and confident in its future by expanding Heathrow."