Security forces in Russia and Ukraine say they have thwarted a plot to assassinate Russian Prime Minister Vladimir Putin.
According to a report on Russian state-run television on February 27, the alleged plot was due to be carried out shortly after Russia's presidential election on March 4.
Channel 1's report showed separate footage of two alleged plotters saying they were ordered by North Caucasus insurgent commander Doku Umarov to kill Putin.
The Interfax news agency has quoted an unnamed law enforcement official as saying the plot was uncovered after Ukrainian intelligence agents detained two Russian citizens in the Ukrainian port city of Odesa early this month in connection with an accidental bomb blast in the city in January.
One of the videos broadcast on Channel 1, provided by the Ukrainian Security Service, shows a suspect called Ilya Pyanzin.
Pyanzin, who is reported to be a 28-year-old Kazakh citizen, said he had traveled to Ukraine from the United Arab Emirates with an accomplice, a Russian national who was later killed in the accidental bomb blast.
Both men said they had been told to make contact with a third suspect, Adam Osmayev, and begin planning an attack on Putin.
"They told us first to go to Odesa and learn how to make bombs, and then go to Moscow to carry out attacks on economic targets, and in the future assassinate Putin," Pyanzin said.
Osmayev, an alleged terrorist trainer who had been on international wanted lists since 2007, was detained by Ukrainian special forces.
Though neither Pyanzin nor Osmayev says so in their videos, Channel 1's report claims the men confessed to having received their orders from Umarov.
Umarov tops Russia's most-wanted list for his role in a number of terrorist attacks, including the January 2011 suicide bombing at Moscow's Domodedovo Airport and the twin suicide attacks in the Moscow subway in March 2010.
Umarov in early February released a video ordering his fighters to halt attacks on Russian civilians, but saying that Russian government and military officials remained legitimate targets.
In an interview with Channel 1, Osmayev, an ethnic Chechen, said he had been instructed to train the other two men to carry out the assassination plot in Moscow.
Channel 1 quoted him as saying the attackers were preparing to use antitank mines in the attack. An unnamed Federal Security Service (FSB) officer is quoted as saying Osmaev's laptop included video footage of a Putin motorcade shot from different angles.
Osmayev also said the slain accomplice, Ruslan Madayev, had also been preparing to launch a suicide attack if the antitank mines failed.
Osmayev said he "would definitely not" carry out a suicide attack, but Madayev "was prepared to go on a suicide mission."
Putin is widely expected to return to the Russian presidency for an unprecedented third, nonconsecutive term. The early years of his first term as president were accompanied by a rise in terrorist attacks attributed to Islamist fighters in the North Caucasus.
Putin's candidacy has sparked a wave of massive opposition protests, with many demonstrators calling for an end to his 12-year domination of Russian politics.
Russia's ITAR-TASS news agency quoted Putin's press secretary, Dmitry Peskov, as confirming the information about the assassination plot but offering no additional comment.
A journalist with the Odesa edition of the newspaper "Porto-Franco," Aleksandr Galyas, told RFE/RL's Russian Service that Ukrainian security officials had offered numerous theories for the men's activities in Ukraine ever since the January bomb blast.
"First they said that the explosion took place while they were planning to assassinate a Ukrainian oligarch," he said.
"In addition, the same computer where they say they found photos and videos of Putin's motorcade, they also found photos of crowded places in Odesa -- the musical comedy theater, the sports palace, the Athena shopping center.
"So they seemed to be suggesting that these comrades were preparing an explosion in the city, at some big gathering point. And all these theories seemed to change at the speed of sound, causing a lot of confusion."
With Interfax, ITAR-TASS, AFP, and AP reporting