UPDATED 6.05pm: Heathrow, Gatwick and Stansted airports will be open and operating on Friday after a foiled terrorist plot threw them into chaos.

But more flights cancellations and delays at Heathrow are expected on Friday.

The strict security measures will also remain in place and are expected to continue to cause delays.

On Thursday over 400,000 passengers have been affected by chaos at airports countrywide. In total, BA has cancelled 400 flights, EasyJet 300 and Ryan Air 46.

BAA, the airports authority, said on Thursday evening: "It is our intention to return to near normal operations, within the new restrictions, tomorrow.

"The additional security restrictions will continue to have an impact on the airport operation.

"However we are working hard, in conjunction with our airlines and control authorities, to deliver as normal a service as possible.

"Some flights will inevitably be cancelled tomorrow. Therefore anyone who intends to travel tomorrow should check with their airline before they leave home for the airport."

The latest advice from BAA is:

  • Heathrow: Airlines are operating short-haul flights into Heathrow. Inbound long-haul flights continue to operate but with delays. Arrival flights average delay time is 30 minutes.

Check-in and hand search processes across all four terminals is severely affected, and will continue throughout the evening. Passengers should check with their airline before travelling to the airport and to expect delays. British Airways has cancelled its short-haul departures schedule for the rest of the day. Average delay time for departures is around 2 hours 30 minutes.

  • Gatwick: The airport itself is experiencing some cancellations and disruption, with an average delay of 1 hour 40 minutes. Check-in and hand search processes across both North and South Terminals are affected, and this will continue throughout the day.
  • Stansted: The airport itself is experiencing lengthy delays and cancellations. Check-in and hand search processes are severely affected, and this will continue throughout the day. Passengers are asked not to come to the airport today unless absolutely necessary.

Luton Airport is currently experiencing delays on most flights and some flights may be subject to cancellation.

London City Airport had a few flights cancelled and delay time of 45 minutes.On Thursday, EasyJet cancelled all of their flights in and out of Gatwick, Luton and Stansted.

Extra security measures include:

  • No items of hand baggage can be carried on board any aircraft departing any UK airport.
  • Passengers may only take through the airport security search point, the following items in a single (ideally transparent) plastic carrier bag: travel documents, wallets and purses, prescribed medicines, sanitary items, spectacles and sunglasses, contact lenses and keys.
  • Parents with young children can take on board baby food, milk, nappies and wipes.
  • Banned items include: mobiles phones, laptops, electrical key fobs, handbags, electrical or battery powered items including laptops, mobile phones, ipods and remote controls.
  • Nothing may be carried in pockets.
  • All passengers must be hand searched, and their footwear and all the items they are carrying must be x-ray screened.
  • Pushchairs and walking aids must be X-ray screened and only airport-provided wheelchairs may pass through the screening point.
  • All liquids must be removed from passengers.

Any customers not complying with the Government instruction will not be accepted for travel.Passengers should allow extra time for their journeys and are being asked for patience as airlines and airports implement the new arrangements.

British Airways said that those customers who do not wish to travel on Thursday may be able to re-book or refund online by December 1. This applies to some ticket types, but not all.

A freephone advice line for UK British Airways passengers is: 0800 727 800.

Passengers departing from airports outside the UK are advised to check www.ba.com for the latest flight information.

EasyJet said passengers booked on cancelled flights will be entitled to a refund or may transfer their flight to a later date free of charge.

Brussels international airport, the German airline Lufthansa, Air Iberia and the Greece national carrier airline Olympic Airlines have cancelled all flights to Britain.There is an increased police presence, including some armed officers, at key sites such as train stations and airports throughout the capital.