MOSCOW — A team of Russian state security agents poisoned prominent opposition activist Alexei Navalny in August, the investigative website Bellingcat claimed in a report Monday, citing telecom and travel data that it says links Moscow with the attempt on Navalny's life and reveals how he has been under constant surveillance for three years.

Bellingcat said the “voluminous” data implicates eight members of a clandestine group of Russia’s FSB, a successor to the Soviet-era KGB responsible for domestic intelligence. The unit specializes in working with chemical weapons, Bellingcat said.

“I know who wanted to kill me,” Navalny said in a video message about Bellingcat’s joint investigation with Russia’s Insider website, Germany’s Der Spiegel news magazine and CNN. “I know where they live. I know where they work. I know their real names. I know their fake names. I have photographs of them.”

Navalny became gravely ill during an Aug. 20 flight to Moscow from the Siberian city of Tomsk; the plane made an emergency landing in Omsk, and Navalny was in a medically induced coma for more than two weeks. The Berlin hospital to which he was later transferred attributed his condition to a toxin similar to the Soviet-era nerve agent Novichok, the same substance that Britain said Russian state security agents used on former Russian spy Sergei Skripal and his daughter in Salisbury, England, in 2018.

The Bellingcat report said that “an analysis of prior travels of the FSB squad members shows they have been shadowing Navalny since at least 16 January 2017, just a month” after Navalny announced he was running for president. It added: “Navalny made over 20 campaign trips outside Moscow during 2017. Members of the squad tailed him on the majority of these, with the exception of a few day trips. . . . In total, the FSB squad made 37 trips to the same destinations that Navalny travelled to by plane or train between 2017 and 2020.”

But most incriminating in the report are the phone records and travel logs that indicated intense communication between the purported FSB officials tailing Navalny and their superiors in Moscow, suggesting that the August attempt on his life was directed by the Kremlin. Russia has ignored calls from Western leaders to investigate the case, citing a lack of evidence.

“Of course an operation of this scale and such duration could not be organized by anyone other than the head of the FSB, [Alexander] Bortnikov, and he would never have dared to do this without [Russian President Vladimir] Putin’s order,” Navalny said.

The European Union imposed sanctions on Bortnikov in October, banning travel and freezing his assets, for his suspected role in Navalny’s poisoning. A separate investigation from Bellingcat in October claimed that Russia continued its Novichok development program long beyond the officially announced closure date, disguising it behind a network of state-run institutes.

The Bellingcat investigation doesn’t say how Navalny was poisoned, but it indicates that it could have been at Tomsk’s Xander Hotel bar the night before his morning flight to Moscow. According to Bellingcat, at about 11:15 p.m., Navalny ordered a bloody mary, but the bartender told him he didn’t have the ingredients for that and suggested a Negroni instead. Navalny told Bellingcat that he couldn’t take more than one sip because “the cocktail tasted like the most disgusting thing I’ve had in my life.”

In his video message Monday, Navalny revealed what he believes was an earlier attempt to poison him. On a vacation to the Russian province of Kaliningrad on the Baltic Coast on July 6, Navalny’s wife, Yulia, felt ill during a walk to a cafe. At the cafe, she was too sick to eat and returned to their hotel, she said. She described being barely able to walk, resting on benches and leaning on trees. At the hotel, she rested and later felt better, according to Navalny.

“A whole FSB department under the leadership of high-ranking officials has been conducting this operation for three and a half years, during which time they tried to kill me and my family members several times using a chemical weapon obtained in a secret state laboratory,” Navalny said Monday. “So it is already an irrefutable fact that we are dealing with a government operation.”

He referred to it as “state terrorism.”