The new limit of 100,000 daily passengers - which amounts to a cut of 4,000 passengers a day - will be in place from Tuesday until 11 September, the airport said.

Heathrow chief executive John Holland-Kaye said in the past few weeks, passenger numbers have regularly exceeded 100,000, leading to "periods when service drops to a level that is not acceptable".

He said airlines, airline ground handlers and the airport were unable to handle such high volumes.

Passengers have faced long queues, delays, last-minute cancellations, late baggage and baggage not making it on to flights.

Without the cap, Heathrow predicted that daily departing seats over the summer would average 104,000 - giving a daily excess of 4,000.

"On average only about 1,500 of these 4,000 daily seats have currently been sold to passengers, and so we are asking our airline partners to stop selling summer tickets to limit the impact on passengers," Mr Holland-Kaye said.

"By making this intervention now, our objective is to protect flights for the vast majority of passengers at Heathrow this summer and to give confidence that everyone who does travel through the airport will have a safe and reliable journey and arrive at their destination with their bags.

"We recognise that this will mean some summer journeys will either be moved to another day, another airport or be cancelled and we apologise to those whose travel plans are affected."

It is estimated that about 93,000 passengers (1,500 over 62 days) are likely to be affected by the news, and they will be contacted by their airline.

Affected travellers will not be entitled to compensation as the reason for the cancellations will be classified as being outside the control of airlines.

Heathrow capacity 'limited by staffing problems'

Mr Holland-Kaye said delays at other airports were having a knock-on effect as passengers were arriving late, adding to pressures on staff.

"Our colleagues are going above and beyond to get as many passengers away as possible, but we cannot put them at risk for their own safety and wellbeing," he said.

He said some "critical functions" are "significantly under-resourced", especially ground handlers, who are contracted by airlines to provide check-in staff, load and unload bags and turn around aircraft.

"This is a significant constraint to the airport's overall capacity," he said.

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Willie Walsh, director general of the International Air Transport Association and a former head of British Airways owner IAG, criticised Heathrow.

He told Reuters: "I am surprised Heathrow have not been able to get their act together better than this.

"Airlines have been predicting stronger traffic than Heathrow has been predicting ... they clearly got it completely wrong.

"To tell airlines to stop selling - what a ridiculous thing for an airport to say to an airline.

"Heathrow are trying to maximise the profitability that they get from the airport at the expense of airlines."