Two senior Russian cyber security officials along with a top anti-hacking expert have been arrested in a US-linked treason case.

A lawyer representing one of the suspects said on Wednesday that Sergei Mikhailov, the deputy head of the FSB's Centre for Information Security, and his deputy Dmitry Dokuchayev along with Ruslan Stoyanov, the head of the investigation unit at Moscow-based cybersecurity giant Kaspersky, had been detained by authorities in Moscow.

Ivan Pavlov said the three were suspected of committing treason. He added that the case was linked to the United States but said the CIA spy agency was not specified in the documents related to the case.

This is believed to be one of the highest-profile treason cases to hit the Russian intelligence community in years.

Authorities have yet to officially confirm the arrests but sources in the Kremlin said President Vladimir Putin had been informed about the case when Russian media were earlier covering it.

Kremlin spokesman Demitry Peskov, however, denied there was any link between the case and recent allegations in the United States that Russia carried out cyber attacks on American organizations with the intention of paving the way for the election of Donald Trump as president.

Peskov said there could be no connection as Russia “categorically denies any claims on the possible Russian involvement” in any hacking.

Pavlov said more suspects were involved in the case but he would not elaborate. If confirmed, the case could be one of the most sensitive affecting Russia’s domestic intelligence agency FSB.

Sources in the CIA also said that they had no comment on the issue.

Kaspersky had confirmed the arrest of its former official last week although it said charges brought against Stoyanov were related to the time he was not an employee of the company.