A record six million passengers passed through Heathrow in May, the airport has confirmed.
The figure represents a 2.2 per cent rise compared to May 2013.
The monthly statistics showed seats per aircraft decreased 0.1 per cent to 202.6, while load factors grew by 0.4 per cent to 75.1 per cent.
“The scale and growth of these important long-haul markets show the unique role of Heathrow as the UK's hub - other London airports like Gatwick or regional airports like Birmingham are important but no substitute for capacity at the hub,” Heathrow said.
In May, Heathrow unveiled its revised proposals for a third runway, which showed how only Heathrow can connect the whole of the UK to growth.