MOSCOW (Reuters) -- A bomb scare in the Russian city of Ryazan that frightened thousands of people and drove many into temporary shelters for the night was only a security exercise, Russia's security chief said on Friday.
Nikolai Patrushev, the head of Russia's FSB domestic security service, told NTV television three sacks of suspected explosives with a timing device found in an apartment block in Ryazan were planted there to test people's vigilance."It was not an explosion somebody foiled, it was a security training exercise. The sacks contained only sugar, there were no explosives inside," he said.
In the early hours of Thursday morning police, alerted by residents of the 12-storey apartment block in Ryazan, 125 miles southeast of Moscow, found three sugar sacks in the basement with a timer and detonators.
The sacks were filled with small crystals that resembled cyclonite, the powerful sugar-like explosive that destroyed several apartment blocks across Russia over the past month, killing up to 300 people.
Police evacuated the building and residents spent the night in a local cinema.
Television showed pictures of shocked and frightened people afraid to return to their flats even after the sacks had been removed from the building.
Many newspapers on Friday reported the foiled bomb attack and carried photofits of the suspected would-be bombers.
The leading business daily Kommersant even tried to explain why the stuff found in the sacks failed to go off when local security officials later attempted to detonate it.
"The terrorists seem to have miscalculated the sugar/explosives proportion," the paper said in a story headlined "Timer stopped seven hours before blast."
Patrushev, apparently unfazed by the hullabaloo, said such exercises should imitate real life as closely as possible.
He said similar devices had been planted in other cities but hinted that residents and officials there had proved less vigilant than in Ryazan.
"Such exercises were not only carried out in Ryazan, and I should single out the people of Ryazan and its forces of law and order for having reacted as they did," he said.
A wave of bombings in Russia this month has killed nearly 300 people and prompted a huge security clampdown. The two biggest explosions destroyed two apartment blocks in Moscow.
Officials have blamed the blasts on Chechen warlords fighting Russian rule in the North Caucasus region of Dagestan. The warlords have denied any involvement but Russia has sealed its administrative borders with Chechnya and is conducting air strikes against what it says are guerrilla targets.
Russian police have detained a number of people suspected of involvement in the blasts but nobody has been formally charged.