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.

Russian security officials in the country's second city of Saint Petersburg have detained alleged members of banned Islamist group Hizb ut-Tahrir, Russia's FSB security agency said Tuesday.

Hizb ut-Tahrir (Party of Liberation) seeks to re-establish a caliphate -- a pan-Islamic state based on Islamic rule harking to the medieval era -- and has been banned in Russia since 2003.

U.S. President Barack Obama arrived on Wednesday in Saint Petersburg for the G20 summit in Russia, where officials said he would argue his case for military action against the Syrian regime over an alleged chemical weapons attack.

With a serious expression, Obama jogged down the steps off his Air Force One plane which touched down at Saint Petersburg's Pulkovo airport ahead of the opening by Russian President Vladimir Putin of the summit later in the afternoon.

Russian Prime Minister Dmitry Medvedev has reinstated the imperial name of a train station outside Saint Petersburg that is used by tens of thousands of tourists visiting the former palaces of the tsars, state media said Sunday.

Medvedev ordered the train station to use its original name of "Tsarskoe Selo" (Tsar's Village), which it lost almost a century ago in 1918 shortly after the Bolshevik revolution and the fall of the Romanov dynasty, according to a government decree.

A court in Russia's northern Kirov region on Friday ordered the release of protest leader Alexei Navalny pending the appeal against his five year sentence on embezzlement charges.

The court ruled that keeping Navalny in custody would deprive him of his right to stand in mayoral elections in Moscow on September 8. Navalny had been accepted as a registered candidate for the polls earlier this week.

A Russian ship that tried to supply attack helicopters to Syria last month before being forced back will dock in Saint Petersburg in coming days, its owners said on Wednesday.

The privately-chartered Alaed had to return to Russia after its initial attempt to deliver the controversial cargo to President Bashar Assad's regime in June was exposed by the U.S. State Department.

Russian protest leader Alexei Navalny led thousands through the streets of Vladimir Putin's native city Saturday in protest against his likely return to the Kremlin in March 4 polls.

The demonstration was called a day before thousands more hoped to link hands around Moscow in a poignant show of frustration with the ex-KGB spy's decision to seek a third presidential term after dominating Russia for 12 years.

Russian riot police arrested dozens of people on Saturday in Moscow and Saint Petersburg who tried to stage unsanctioned New Year's Eve protests against 12 years of Vladimir Putin's dominant rule.

The show of police force marked the first time the authorities had cracked down on members of the Russian opposition since allowing two massive rallies on December 10 and December 24.

Russian security services have foiled a plot by a group of Islamists to blow up a high-speed train running between Moscow and Saint Petersburg, the Kommersant business daily said Monday.

A blast on the same route that authorities blamed on Muslim rebels killed 26 people in November 2009.