Heathrow airport said “the case for expansion has never been clearer” after it was overtaken as Europe’s busiest airport by Istanbul.

Figures published on Tuesday showed 7.86 million passengers passed through Heathrow’s four terminals in July, compared with Istanbul’s 8.15 million.

Heathrow’s passenger numbers for July fell, while London Stansted and Manchester both had record traffic for the month.

Annual figures from the trade body Airports Council International show Heathrow was Europe’s busiest airport from 1996 to 2019.

The UK’s biggest airport, located west of central London, lost that position in 2020 amid coronavirus travel restrictions before regaining it in 2023 and holding the title since then.

Heathrow’s July passenger total was 1.5% down compared with the same month last year, while the Turkish hub recorded a 2.3% increase.

The US-Israel war on Iran has affected Heathrow’s passenger traffic. Numbers on Middle East routes were down 20.2% year on year in July.

Heathrow continues to operate its two runways at near full capacity, and is seeking government permission to build a third.

An expansion proposal by the airport’s owners would enable it to accommodate 150 million passengers a year - up from about 85 million in 2025.

The airport said: “Heathrow is operating at capacity. The case for expansion has never been clearer, as Heathrow was overtaken in July by Istanbul airport as the busiest hub in Europe.

“Our plans will ensure the country gets the infrastructure it needs to stay competitive and will deliver all-important economic growth.”

The comparison, however, may not fully bolster Heathrow’s case. The airport was only opened in late 2018 and built on a brand new site away from the city and residential neighbourhoods, gradually replacing the existing Ataturk airport as the main international hub. It has a vastly bigger footprint and is able to operate 24 hours a day.

The Turkish boom also owes much to its location near the Gulf, which has become the crossroads of international air travel.

The transport secretary, Heidi Alexander, launched a consultation on the renamed Heathrow expansion national policy statement in June, setting out the conditions needed if the project is to be given the go-ahead.

The then chancellor, Rachel Reeves, said at the time she was determined to get “spades in the ground” for the third runway in the current parliament, and for it to be built by 2035.

Andy Burnham, who sacked Reeves, has previously expressed concerns over Heathrow expansion, stating the plans divert infrastructure investment “away from the north and traps it in London”.

Heathrow’s chief executive, Thomas Woldbye, said summer was “off to a flying start” but “we want to go further” by “growing our route network and passenger offering”.

“Expanding Heathrow will help ensure the UK remains home to Europe’s leading hub and continues to benefit from the trade, investment and tourism that increased connectivity will bring,” he said.

London Stansted said it had recorded the busiest month in the airport’s history in July, welcoming 3.1m passengers, a 6.3% increase year-on-year.

Manchester also had a record July, serving 3.4m passengers.