Prime Minister Vladimir Putin, second right foreground, and Emergency Minister Sergei Shoigu, right, visiting the Sayano-Shushenskaya hydroelectric power plant in southern Siberia on Friday.
Officials were quick to cast doubt on the announcement, which appeared timed to coincide with Prime Minister Vladimir Putin's arrival at the Sayano-Shushenskaya hydroelectric plant with a group of ministers on Friday.
The group, which calls itself Riyadus Salikhiin, said in a statement posted on the rebel web site Kavkazcenter that Chechen rebels decided earlier this year to step up an "economic war" against Russia and sent several sabotage groups into the Russian regions.
The groups were supposed to disrupt the work of the oil and gas pipelines, electric power stations and industrial enterprises, the statement said.
The statement said Monday's accident at the Sayano-Shushenskaya hydroelectric plant, in which at least 30 people died and 45 were missing as of Friday at noon, was caused by an anti-tank grenade with a timer, installed in the plant's turbine room.
The rebels pledged to continue similar attacks, arguing that the "anxiety of the infidels' leadership demonstrated that this operation delivered them a big blow."
The group was created in 2002, when then-rebel leader Shamil Basayev claimed it included potential suicide fighters to carry out the most high-profile terrorist attacks. The letter posted Friday also claimed responsibility for a suicide car bombing on Monday of a police station in Nazran, which killed 24 people and wounded more than 200.
A Kremlin spokesman on Friday shrugged off the Chechen rebel claims as "idiotic."
"We are not going to comment on idiotic claims," the Kremlin source told Reuters, without elaborating further.
Investigative Committee spokesman Vladimir Markin told Interfax that nothing indicated there was a terrorist attack directed against the power plant.
"The FSB's specialists have not found traces of explosives at the site of the accident," he said.
A spokesman for the Federal Security Service contacted by The Moscow Times on Friday afternoon declined comment.
Energy Minister Sergei Shmatko ruled out terrorism as a possible cause of the dam accident on Wednesday, but neither he nor Emergency Situations Minister Sergei Shoigu has come up with a convincing explanation of what could have caused the flood. Both called the disaster "mysterious" this week.
Shmatko, Shoigu and other officials accompanied Putin on Friday during his tour of the recovery and rescue efforts in Khakasia.
While Riyadus Salikhiin has committed some of Russia's worst terrorist attacks in recent years, Chechen rebels have also been known to claim responsibility for events they had nothing to do with.
Chechen rebels said they were behind a torpedo explosion that sank the Kursk nuclear submarine and its crew of 118 in August 2000. Later that month, rebels also said they caused a fire at the Moscow's Ostankino television tower that left three dead.
In 2005, the rebels said they blew up an electric transformer in southeastern Moscow, after which almost a third of the city experienced power shortages for several hours.
Rebel involvement was never confirmed in any of those cases.