British Airways has suspended all flights to Cairo after heightened terrorist activity in the region, leaving the holiday plans of hundreds of families in chaos as the school summer break begins.

German airline Lufthasna has also announced it has temporarily suspended flights from the Egyptian capital.

The decision reportedly follows growing concerns about ISIS activity in Egypt.

ISIS fighters operate within the Sinai peninsula in Egypt but there are indications their activities are spreading, including to the capital city.

Passengers were queuing up to board the aircraft when they were told the service was cancelled and there would be no further flights to Cairo with British Airways for seven days

ISIS terrorists bombed a Russian jet over Egypt's Sinai desert in 2015 killing all 224 on board. Britain banned flights to beach resort Sharm el-Sheikh after the incident.

Passengers about to board a BA flight from Heathrow to Cairo yesterday were told their flight had been cancelled and there would be no alternative BA flights for seven days.

A passenger on the cancelled BA155 flight was given a letter from the airline. It said: 'We constantly review our security arrangements at all our airports around the world and have suspended flights to Cairo for seven days as a precaution to allow for further assessment.'

British Airways flight BA 154 left Cairo Airport and arrived in London at lunchtime yesterday

Official Foreign Office advice, updated on Friday, said: 'There's a heightened risk of terrorism against aviation. Additional security measures are in place for flights departing from Egypt to the UK.'

Flight BA154 from Cairo to Heathrow landed in London today at 12.28, 18 minutes behind schedule without incident.

However, the return journey to the Egyptian capital was called off. An Air Canada flight, which is a code share with Egypt Air is due to depart for Cairo at 10:10pm.

Lufthansa said is planned to resume flights later today.

The airline said in a statement: 'As safety is the number one priority of Lufthansa, the airline temporarily suspended its flights to Cairo on July 20 as a precaution.

'Normal operations will resume Sunday and all flights are scheduled to operate.'

The Foreign Office told MailOnline they are currently updating their travel advice for British Citizens planning to visit Egypt following British Airways' announcement

Passenger Christine Shelbourne, 70, from Surrey was in Heathrow with her 11-year-old grandson having checked in for the flight.

However, when she got to the barriers, her boarding card was not working.

She told the BBC: 'The check-in staff reissued my boarding pass and I tried again but that didn't work either and we were told to try again in half an hour.

'Whether they knew anything I don't know but my husband told me the flight had been cancelled before they did. There were no suggestions or help from staff about alternative flights.'

'My 11-year-old grandson is heartbroken - he's been looking forward to the trip for months. We're just not going now,' she added. It was handled badly to be honest. My grandson is currently looking for flights for us - he's devastated.'

One customer, Rasha, who asked to keep her surname private said she was booked on a flight on July 25 but was alerted by text about the suspensions.

Passengers in the queue were handed this letter which advised them of their rights

The IT worker, who is from Egypt and has lived with her family in Britain for six years, said she was supposed to meet her husband, children and other relatives.

'It's just terrible,' she said. 'It may seem like I'm just missing my flight for a holiday, but I really need to go.'

One angry passenger tweeted: 'Currently about to board a @British_Airways flight to Cairo and it's cancelled.

'Not for a day. Not for two days but for seven. Security risk. Someone knows something we don't.'

The Foreign and Commonwealth Office has warned that flights to Egypt face 'a heightened risk of terrorism'.

British Airways said: 'We constantly review our security arrangements at all our airports around the world, and have suspended flights to Cairo for seven days as a precaution to allow for further assessment.

'The safety and security of our customers and crew is always our priority, and we would never operate an aircraft unless it was safe to do so.'

The airline has offered food and hotel vouchers for stranded passengers.

British Airways has cancelled all flights to Cairo for seven days as a 'precaution'

Some affected passengers used social media to share pictures which appeared to show a letter handed out by British Airways with a similar message about security.

A spokeswoman for the airline said it could not immediately offer more information about the suspensions.

The airline normally offers one return service between Heathrow and Cairo a day - apart from Wednesday.

BA said they are re-evaluating the security situation at Cairo Airport, pictured, before making a decision to resume flights. They confirmed the process will take at least seven days

Despite the decision by British Airways, Air France's AF570 service from Paris took off on time.

Three Egyptian airport security sources told Reuters that British staff were checking security at Cairo airport on Wednesday and Thursday. They provided no further details.

The British Foreign Office advises against all but essential travel by air to and from the Egyptian resort of Sharm el-Sheikh, but has not issued similar warnings against air travel to and from Cairo.

According to the Foreign Office: 'There's a heightened risk of terrorism against aviation. Additional security measures are in place for flights departing from Egypt to the UK. You should co-operate fully with security officials at airports.'

The Egypt State Information Service could not immediately be reached for comment.

A Government spokesperson said: 'We are aware that British Airways is notifying passengers that it has decided to suspend flights to Cairo temporarily.'

An estimated 415,000 British nationals visited Egypt in 2018.

The airline was also among several major carriers to announce in June they would reroute flights to avoid the Strait of Hormuz.

The move - also taken by Australia's Qantas, Dutch carrier KLM, Emirates, Germany's Lufthansa, Malaysia Airlines and Singapore Airlines - followed the downing of a US drone by Iran.

Passengers due to fly to Cairo are advised to call BA on 0844 493 0787.