More than 10,000 passengers flying in and out of London Heathrow have been affected by cancellations and delays after thick fog swept across Europe's busiest airport this morning. If your flight's been cancelled you should be able to claim a refund or rebook, but you may have to grin and bear it if you've been delayed.

More than 100 flights have been affected at Heathrow, with about 90 cancelled and dozens more delayed. The message coming out of Heathrow is to check with your airline before travelling.

A Heathrow spokesperson says: "Foggy weather across the south east has reduced visibility at Heathrow. As a result, some passengers may experience disruption to their journeys today. 

"Passengers should check their flight status with their airline before coming to the airport. Heathrow's top priority is the safety of passengers and we apologise to those whose travel has been affected."

While most of the disruption is centred at Heathrow, other airports in the south east have been affected to a lesser extent. More than 30 flights serving London City Airport have been cancelled because of fog, Gatwick has cancelled one flight and warned delays are likely, while Stansted has yet to cancel any flights.

If your flight has been cancelled because of the weather then your airline will most likely give you the option of a refund on your ticket or rebooking an alternative flight. However, because the issue is outside airlines' control, you're unlikely to be able to claim any money back if your flight's been delayed.

Check out our Flight Delays guide for full details.

What are my rights?

Under EU regulations, you're entitled to the following:

  • If flights are cancelled at short notice: Airlines must normally give you a full refund of any unused ticket or offer suitable alternative travel. 

  • If flights are delayed: You're only entitled to compensation if the delay was caused by something within the airline's control. Extraordinary circumstances aren't covered, and airlines may well classify severe weather conditions as an extraordinary circumstance. 

    But you can still try asking the airline if it will compensate you – and if it turns you down and you disagree with the decision you can challenge it. European guidelines state that the airline must prove there were extraordinary circumstances and it took all reasonable steps to avoid them.

    If your departure is delayed by over five hours, you can choose not to travel on the delayed flight and get a refund for that trip and for later flights on the same ticket. For full details on your rights, see our Flight Delays guide.

Heathrow flights cancelled and delayed amid heavy fog – your rights
You're only entitled to compensation if the delay was caused by something within the airline's control

Which airlines have cancelled flights?

Flights operated by British Airways (BA) have suffered the lion's share of disruption, with the airline cancelling 80 flights so far this morning – mostly domestic services or short-haul European flights.

A BA spokesperson says: "We're sorry that some of our customers' travel plans have been affected due to the forecast fog at Heathrow, which will lead to a reduction in the number of aircraft which can land each hour.

"For safety reasons Heathrow Airport, air traffic control and airlines have agreed to operate a slightly reduced schedule to help mitigate the effects of the fog. We are refunding or rebooking any affected customers onto alternative flights so they can continue their journeys as soon as possible."

Meanwhile, other airlines have cancelled about 20 short-haul flights, with Aer Lingus, KLM, Lufthansa, Swiss and SAS Scandinavian Airlines among those affected.

Contact your airline ASAP if you're unsure whether or not your flight has been affected.