A major terror attack on Moscow was foiled by the country's top security agency, officials said.
Alexander Bortnikov, director of the federal security service or the Federal'naya Sluzhba Bezopasnosti (FSB), reported to President Dmitry Medvedev that they have detained four men who came to Moscow from the North Caucasus region for an attack on the city's transportation system, Xinhua reported.
He did not disclose how the suspects were found and arrested, but said a self-made 10-kg bomb, maps and weapons were seized from them.
All the detained men have confessed to the crime, he said.
Over the past six months, a total of 169 terror-linked crimes have been committed in Russia, which was 58% less than last year, officials said.
Most of the crimes took place in the North Caucasus republic of Dagestan.
The FSB prevented another 52 terror attacks in the first half of 2011, seizing 280 bombs and over 500 kg explosives. Some 400 terrorists were arrested and 250 militants were killed in these operations.
The director said that in these operations, FSB lost 95 officers and 200 were wounded.
In January, suicide bombers from the North Caucasus region detonated a bomb in Moscow's Domodedovo international airport, killing 37 people. Last year, two women bombers from the same region set off twin blasts in the Moscow metro, killing 40 people.