Russia has grounded Airbus A321 jets flown by the Kogalymavia airline, Interfax news agency reported on Sunday, after one of its fleet crashed in Egypt's Sinai Peninsula, killing all 224 people on board. The A321, operated by the Russian airline under the brand name Metrojet, was carrying holidaymakers from the Red Sea resort of Sharm El-Sheikh to St Petersburg when it went down soon after daybreak on Saturday. Interfax said the Russian transport regulator Rostransnadzor had told Kogalymavia to stop flying A321 aircraft until the causes of the crash were known. However, RIA news agency cited a Kogalymavia representative as saying that the airline had not received the order from Rostransnadzor. United Arab Emirates airlines Emirates, Air Arabia and flydubai said on Sunday they were re-routing flights to avoid flying over Egypt's Sinai Peninsula. Re-routing usually means longer flying distance, which adds to fuel costs. The airlines said they were closely monitoring the area and the re-routing was a security precaution, according to separate emailed statements to Reuters. German carrier Lufthansa and Air France have also announced they will no longer fly over the Sinai until the cause for the plane crash had been identified. Germany's Transport Ministry has warned the country's airlines to avoid flying over both the northern and southeastern parts of the Sinai Peninsula following the crash of a Russian passenger plane. A spokesman said Sunday that, because of Saturday's plane crash in Sinai that killed 244 people, the ministry has issued "until further notice a broad warning ... for using flight routes in the southeastern Sinai." Egyptian and Russian investigators will begin examining within hours the contents of two "black box" recorders recovered from the airliner, which crashed into a mountainous area of central Sinai shortly after losing radar contact near cruising altitude. A militant group affiliated to Daesh in Egypt said in a statement that it brought down the plane "in response to Russian airstrikes that killed hundreds of Muslims on Syrian land", but Russia's Transport Minister Maxim Sokolov told Interfax news agency the claim "can't be considered accurate". Egyptian Prime Minister Sherif Ismail told a news conference late on Saturday that there did not appear to be any unusual activity behind the crash but added that the facts would not be clear until further investigations had been carried out. Sokolov and a team of investigators arrived at the scene on Sunday and experts would begin examining the black boxes at the Civil Sviation Ministry in Cairo within hours, judicial and ministry sources said. It was not clear how long the contents of the boxes, which record flight data and cockpit conversations, would take to retrieve. Russian transport prosecutors have already examined the quality of the fuel used by the airliner and found that it met necessary requirements, Russia's state-run RIA news agency said. The crew had also undergone medical tests recently and no problems were detected, Interfax reported. At least 163 bodies had already been recovered and transported to various hospitals including Zeinhom morgue in Cairo, according to a Cabinet statement. Russian experts had already visited the morgue on Saturday night and Russia's emergency minister said in a televised statement that 120 bodies had been examined and were being prepared to return home. They were expected to begin arriving in St Petersburg late on Sunday or early on Monday. Those on board included 214 Russians, at least three Ukrainians and one Belarusian, most returning from holidays on the Red Sea, popular with Russians seeking winter sun. The Russian flag was flying at half-mast over the Russian Embassy in Cairo on Sunday morning. President Vladimir Putin has declared a day of national mourning in Russia. Emergency services and aviation specialists resumed their search at the crash site which is spread over more than 15 square km early on Sunday with 100 Russian emergency workers on their way to help recover bodies and gather evidence. The A321 is a medium-haul jet in service since 1994, with over 1,100 in operation worldwide and a good safety record. It is a highly automated aircraft relying on computers to help pilots stay within safe flying limits. Airbus said the A321 was built in 1997 and had been operated by Metrojet since 2012. It had flown 56,000 hours in nearly 21,000 flights. According to FlightRadar24, an authoritative Sweden-based flight tracking service, the aircraft was descending rapidly at about 6,000 feet (1,800 meters) per minute when the signal was lost to air traffic control.