MOSCOW (AP) — Russian news agencies are reporting that former members of the domestic security agency and a cybersecurity expert have been formally charged with treason.

Reports emerged last week that three officials of the Federal Security Service (FSB) and an executive for cybersecurity company Kaspersky Labs had been arrested for treason. Government officials haven't commented on the case.

Speculation on the arrests ranges from fallout from alleged Russian hacking of the U.S. presidential election to a power struggle within Russia's security services.

Ivan Pavlov, a lawyer specializing in treason cases, was quoted by the Interfax and state Tass news agencies as saying that FSB officials Sergei Mikhailov and Dmitry Dokuchayev, and Kaspersky's Ruslan Stoyanov, were charged on Wednesday.

Pavlov has told The Associated Press that he represents the fourth, unnamed arrestee.