Egyptian military prosecutors ordered on Monday the detention of investigative journalist and rights activist Hossam Bahgat on suspicion of publishing false information, the news site for which he works said.

The Mada Masr website said Bahgat, 37, was ordered detained for four days for questioning on suspicion of "spreading false news aimed at harming national interests."

Saint Petersburg on Sunday remembered the victims of the Sinai plane crash, with the bell of the iconic St. Isaac's Cathedral tolling 224 times in memory of each person killed.

At an emotional memorial service at one of the former imperial capital's most famous symbols, a chamber choir sang as several hundred mourners looked on.

Moscow and London ramped up efforts Sunday to bring home thousands of tourists stranded in Egypt's Sharm el-Sheikh resort following the crash of a Russian airliner in the Sinai Peninsula.

Britain and the United States, as well as international investigators, suspect a bomb exploded on board the Russian Airbus after it took off from the Red Sea resort last Saturday en route to Saint Petersburg, killing all 224 people on board.

President Vladimir Putin on Friday suspended Russian air traffic with Egypt and ordered assistance in bringing Russian nationals home as investigators probe why one of its passenger jets crashed in the Sinai.

The Russian president has ordered "the halting of flights with Egypt until we manage jointly with our Egyptian partners to establish the necessary level of provision of security for air travel," Peskov told journalists.

Campaigners opposed to Egyptian President Abdel Fattah al-Sisi on Thursday blocked the entrance to Downing Street, the London residence of British Prime Minister David Cameron, ahead of a meeting between the two leaders.

Around 200 demonstrators protested against Sisi's human rights record, but they were outnumbered by those proclaiming support for the Egyptian leader.

Egyptian President Abdel Fattah al-Sisi defended his sweeping security laws ahead of his arrival in London on Wednesday for talks with British Prime Minister David Cameron.

Sisi has left Cairo for London, where he will hold talks with Cameron on security cooperation on Thursday.

Egyptian President Abdel Fattah al-Sisi called for NATO powers to help rebuild Libya, beset by violence since an uprising backed by the Western military alliance toppled leader Moammar Gadhafi, in an interview on Tuesday.

Sisi was quoted in British newspaper the Daily Telegraph ahead of a visit to London in which he is to discuss security co-operation with Prime Minister David Cameron.

Investigators on Tuesday began examining the two black boxes from the Russian airliner that crashed in Egypt's Sinai Peninsula, as President Abdel Fattah al-Sisi said the probe would take time.

Sisi described a claim by the Egyptian branch of the Islamic State jihadist group that it downed the Airbus A321 that crashed on Saturday killing all 224 people on board as "propaganda."

Egyptian President Abdul Fattah al-Sisi has dismissed as "propaganda" claims by a branch of the Islamic State group that they were responsible downing a Russian plane, the BBC reported Tuesday.

His remarks came as a top U.S. intelligence official said it was "unlikely" IS had been involved in the Kogalymavia airline disaster over the Sinai peninsula that killed 224 people on Saturday.

The Russian passenger jet that crashed in Egypt killing all 224 people on board came down due to "external" factors, the airline said Monday, as relatives began identifying their loved ones in Saint Petersburg.

Senior Kogalymavia executive Alexander Smirnov said that "no technical failures" could account for why the Airbus 321 would have broken up in mid-air, as investigators have said happened.