Blast Near FSB Security Service Academy in Moscow

An explosion went off Wednesday at a bus stop close to the training center for Russia's FSB security service in Moscow, without causing casualties, the national anti-terror committee said.

"An explosive device went off at a bus stop at Michurinsky Avenue where the FSB academy is located," a committee spokesman told Agence France Presse.

"At the same time it is too early to say if the blast was directed at the academy," he added.

The national anti-terror committee is part of the FSB.

Such explosions are a near daily occurrence in the North Caucasus where Russian forces are fighting Islamist rebels but are relatively rare in Moscow.

The explosion comes after a blast in January killed 37 people and wounded more than 100 in Moscow's busiest airport. After a lull of several years, suicide attacks returned to Russia last March when two female suicide bombers from the Caucasus killed 40 and wounded dozens on the Moscow underground.

One of those two underground blasts occurred near the FSB headquarters in central Moscow that some experts have said was hardly a coincidence.

Russia's leading Islamist rebel Doku Umarov has claimed both attacks and vowed to make 2011 "a year of blood and tears."

After Wednesday's blast police heightened security measures around Moscow and the city's police chief went to the scene, Interfax quoted a police spokesman as saying.

Citing a source in law enforcement, Intefax said the explosive device was stuffed with nuts and bolts.

"It looks like militants," the source said, adding however that radical nationalist groups could also be involved.

The source also told Interfax the blast might be a maneuver to draw police attention away from a "more serious crime," another signature tactic of Islamist rebels fighting the Russian security forces.