By Alissa de Carbonnel and Steve Gutterman
MOSCOW (Reuters) - Russian authorities said on Tuesday they had foiled a plot by Islamist radicals to bomb a chemical weapons facility and had arrested two suspects from the North Caucasus, where Moscow is battling an Islamist insurgency.
Militants have previously carried out deadly bombings in Moscow and other parts of Russia outside the mostly Muslim North Caucasus, but specific allegations of plots to attack sites holding weapons of mass destruction in nuclear-armed Russia are almost unheard of.
Authorities believe the suspects planned to build a bomb and attack the Maradykovsky chemical weapons storage and disposal facility in the Kirov region, about 1,000 km (620 miles) northeast of Moscow, the Federal Investigative Committee said.
"The suspects planned a terrorist attack ... that could have risked killing hundreds of people," it said in a statement.
It said the men had traveled north to the remote Kirov area from Moscow to plan the attack and it identified them as followers of Wahhabism - an ultra-conservative branch of Sunni Islam that is practiced in Saudi Arabia and which has become a derogatory term for Islamist radicalism in Russia.
Investigators found bomb components and "literature with extremist content" in an abandoned house in the area where the suspects, aged 19 and 21, were living, the committee said.
It said the suspects were natives of the North Caucasus, a mountainous southern region not far from the Black Sea city of Sochi, where Russia hosts the 2014 Winter Olympics in February. The region is some 2,000 km (1,200 miles) from Kirov.
Insurgent leader Doku Umarov, a Chechen, has urged fighters to use "maximum force" to stop the Olympics taking place.
President Vladimir Putin has staked his reputation on the Games and ordered authorities to boost security in the North Caucasus, where the Islamist insurgency is rooted in two post-Soviet wars pitting Chechen separatists against the Kremlin.
After suicide bombings that killed dozens in the Moscow subway in 2010 and at a Moscow airport in 2011, Umarov called for more attacks on infrastructure in the Russian heartland, but no other major attacks have occurred outside the North Caucasus.
Russia inherited the Soviet Union's declared stockpile of 40,000 metric tons of chemical weapons.
In 1997 Moscow ratified the Chemical Weapons Convention, which requires member states to declare and dispose of all chemical weapons and production facilities.
Russia and the United States had pledged to destroy their chemical arsenals by 2012 but both missed the deadline. They have recently led diplomatic efforts to ensure Syria starts destroying its own chemical weapons stockpile.
As of March 2013, Russian authorities had destroyed more than 90 percent of the chemical weapons at the Maradykovsky facility and were disposing of stocks of the nerve agent soman, according to the Kirov regional government website.
(Editing by Gareth Jones)