LONDON - As the race was on at snowbound European airports Wednesday to clear the backlog of stranded passengers in time for Christmas as weather conditions eased slightly, Cairo Airport rerouted six incoming flights to internal Egyptian airfields due to heavy fog. Thousands of weary passengers woke up in airport terminals around the continent, where stranded travellers have been bedding down since Friday, still in the hope of making it to their destination before Christmas Day on Saturday. Hopes were lifted at London Heathrow Airport after the second runway reopened, but the backlog at a traditionally busy time of the year meant services were not immediately back to normal. Around 1,000 passengers woke up in the terminals at Heathrow, the world's busiest international passenger airport, which has slimmed down its schedule in a bid to manage the situation. Airlines were told what capacity was available and they themselves decided which flights to cut, with both long-haul and short-haul services scrapped. "We're running 70 per cent of our normal planned schedule, which accounts for around 900 flights, and we're comfortable that we'll be able to remove the rest of the snow from the airfield today," a Heathrow spokeswoman said. "Both runways are open and operating," she said, adding that a total of 30,000 tonnes of snow had been shifted from the apron. In Paris, however, around 15 per cent of flights at Paris Charles de Gaulle airport are cancelled Wednesday and 25 per cent are expected to be cancelled Thursday as the return of heavy snow is expected to renew travel chaos. Civil aviation authority DGAC said in a statement that snow "will disrupt air traffic at Paris region airports". Eurocontrol, the continent's air traffic supervisory body, said about 3,000 flights had been cancelled across Europe on Tuesday, with similar numbers of cancellations for each of the past four days. Meanwhile, Cairo Airport authorities rerouted six flights due to the heavy fof which reduced the visibility to less than 200 metres. "Two flights coming from Casablanca and Nairobi were rerouted to Luxor and two others from Addis Ababa and Abuja landed in Sharm el-Sheikh as two internal flights coming from Alexandria and Sharm flew back to their departure airports," a Cairo Airport official said. He added that flights to London were resumed while others to Paris were delayed seven hours due to bad weather. Weather reports said snow could persist in northern Europe, which might hamper flight operations at airports that feed flights into key European hubs.