Egyptian security forces shot dead 24 Isis militants in central Sinai, 70 km from the crash site of the Russian passenger plane the group claimed it brought down, security sources have said.

Security sources said they killed the militants as they hid inside a cave in a mountainous area and that they arrested eight of them.

Russian passenger plane crashes in Egypt Show all 20 1 /20 Russian passenger plane crashes in Egypt Russian passenger plane crashes in Egypt Egyptian soldiers collect personal belongings of plane crash victims at the crash site of a passenger plane bound for St. Petersburg in Russia that crashed in Hassana, Egypt's Sinai Peninsula Russian passenger plane crashes in Egypt Egyptian soldiers collect personal belongings of plane crash victims at the crash site of a passenger plane bound for St. Petersburg in Russia that crashed in Hassana, Egypt's Sinai Peninsula Russian passenger plane crashes in Egypt In this Russian Emergency Situations Ministry photo, made available on Monday, Nov. 2, 2015, showing Metrojet Airbus A321-200 flight 7K9268 flight recorder on display at an undisclosed location in Egypt Russian passenger plane crashes in Egypt Mourners lay flowers at Pulkovo International Airport outside St. Petersburg. Russia on 1 November mourned its biggest ever air disaster after a passenger jet full of Russian tourists crashed in Egypt's Sinai, killing all 224 people on board. Flags were at half mast on the parliament building, in the Kremlin, and on other official buildings in honour of the victims, most of whom were from Russia's second-largest city of Saint Petersburg Russian passenger plane crashes in Egypt People pay their respects at the entrance of Pulkovo airport outside St. Petersburg, during a day of national mourning for the plane crash victims Russian passenger plane crashes in Egypt Debris from the plane crash in Egypt Russian passenger plane crashes in Egypt A piece of an engine of Russian MetroJet Airbus A321 at the site of the crash in Sinai, Russian passenger plane crashes in Egypt The crash site debris Flight 7K9268 crashed in the Sinai peninsula, in all probability killing every one of the 224 people on board AFP/Getty Russian passenger plane crashes in Egypt The crash site debris Debris lies strewn across the sand at the crash site EPA Russian passenger plane crashes in Egypt Relatives in St Petersburg Relatives react after a Russian airliner with 217 passengers and seven crew aboard crashed, as people gather at the Kogalymaviaís information desk at Pulkovo airport in St Petersburg on 31 October AP Russian passenger plane crashes in Egypt Relatives in St Petersburg A relative of a passenger of MetroJet Airbus A321 at Pulkovo II international airport in St Petersburg, Russia, 31 October 2015. EPA Russian passenger plane crashes in Egypt The plane's journey The plane's last recorded radar position above the northern Sinai peninsula Flightradar24 Russian passenger plane crashes in Egypt Where it crashed A satellite view from Google Maps of the rough area where the plane crashed, in the mountainous Hassana region of the Sinai peninsula. Google Maps Russian passenger plane crashes in Egypt The plane The Metrojet's Airbus A-321 with registration number EI-ETJ that crashed in Egypt's Sinai peninsula REUTERS/Kim Philipp Piskol Russian passenger plane crashes in Egypt The plane The crashed Airbus A321 at Domodedovo international airport, outside Moscow,, on 20 October Russian passenger plane crashes in Egypt Relatives at in St Petersburg A relative of a passenger on MetroJet Airbus A321 at Pulkovo II international airport in St Petersburg EPA Russian passenger plane crashes in Egypt Relatives at in St Petersburg Relatives of passengers of MetroJet Airbus A321 at the Crown Plaza hotel in St Petersburg EPA Russian passenger plane crashes in Egypt Bodies being repatriated An Egyptian soldier prays as emergency workers prepare to unload bodies of victims from a police helicopter to ambulances at Kabrit military airport on 31 October. AP Russian passenger plane crashes in Egypt Bodies being repatriated Ambulances line up as emergency workers unload bodies at Kabrit military airport, 20 miles north of Suez, on Saturday AP Russian passenger plane crashes in Egypt Bodies being repatriated Egyptian paramedics load the corpses of victims into a military plane at Kabrit military air base by the Suez Canal on October 31, 2015 AFP/Getty Images

Sinai Province, Isis's Egypt branch, is active in North Sinai where two years ago it launched an insurgency and has since killed hundreds of soldiers and policemen. It is rarely active outside that area.

Western governments said it was likely that the Russian airliner that crashed in the Sinai on Oct. 31 killing all 224 people on board was brought down by a bomb and Isis claimed it was behind the crash.

Egypt says the bomb theory is premature and that only the conclusion of an official investigation will shed light on what brought down the Airbus 321.

Sinai Province said in a statement on the day of the crash that it had brought down the plane in response to Russian air strikes in Syria.