Russian authorities have charged two former officers in the Federal Security Service and an employee of cyber security firm Kaspersky Lab with committing treason in the interests of the United States, according to a lawyer representing one of the three.
Ivan Pavlov identified the three on Wednesday as Kaspersky employee Ruslan Stoyanov and FSB officers who specialised in cyber security, Sergei Mikhailov and Dmitry Dokuchayev.
"My client, along with the others, has been charged with state treason and cooperating with US intelligence services," Pavlov told Reuters news agency in a telephone interview.
He declined to say which of the three he was representing, saying only that Stoyanov was not his client.
The Kaspersky team headed by Stoyanov has been cooperating with the FSB since 2013 in analysing cybercrime cases and offering expertise in criminal cases concerning cybersecurity, Russian newspaper Kommersant reported.
Kaspersky Lab confirmed Stoyanov's arrest but said the charges related to a period before he joined the company in 2012.
Al Jazeera's Rory Challands, reporting from Moscow, said that the trio were arrested late last year, adding that the charges were likely to carry between 12 and 20 years of prison terms.
"The news of the arrest didn't come out until mid-January. Now we've had some charges announced. The big question is - and it is unanswered at the moment - what were they doing?" he said.
"There are a couple of not necessarily mutually exclusive theories about this. One is that when the CIA said that it had high confidence that Russia was behind the hacking of Democratic Party National Congress emails in the run-up to the US presidential elections, it was information from these guys that gave the CIA that high confidence," Challands said.
"Another theory is that these people were running a kind of shadow hacking group motivated primarily by profit - selling information on important people to anyone who would buy it, private buyers or foreign intelligence services."
According to the Russian news agency TASS, the Kremlin rejected speculation that the arrested FSB officers were complicit in hacking attacks during the US presidential election.
Kremlin spokesman Dmitry Peskov said Russian President Vladimir Putin was aware of media reports about the arrests but that the Kremlin could not confirm anything about them.
Source: Al Jazeera and news agencies