Moscow police have arrested two men armed with explosives-packed belts of the kind usually worn by suicide bombers, police sources said.
Interfax news agency described the men, arrested in southwestern Moscow, as Chechens, but said it had no official confirmation of the arrests.
FSB (security service) officers and mine-clearance experts were heading to the scene, Interfax said, also quoting police sources.
"One of the belts has already been taken from one of the individuals and disassembled. It contained explosives stuffed with metal balls," Interfax quoted a source as saying.
A police source quoted by the ITAR-TASS news agency said the men, aged between 22 and 25, were arrested at a shopping mall.
From each, FSB forces removed a belt to which were attached fragmentation grenades and small packets of explosives, the source said, adding that the men may have been preparing an attack on a densely-populated public place.
Contacted by AFP, neither the FSB nor the Moscow police were prepared to confirm the arrests.
Russian police have stepped up security checks around Moscow since Chechen rebels seized a theatre last October taking more than 800 people hostage. At least 129 people died during the hostage crisis, most of them victims of the gas used by security forces to stun the rebel commando.
The rebels said they launched the operation to force Russia to order a withdrawal of its forces from Chechnya, where Moscow has been engaged in a massive counter-insurgency operation for the past three years.
AFP