Russian intelligence 'most likely' behind plane crash that killed Wagner's head: UK media

British security sources claimed on Thursday that Russia's intelligence agency is most likely behind the plane crash that killed all 10 passengers on board, including Wagner mercenary group head Yevgeny Prigozhin, according to media reports.

UK defense sources told BBC that Russia's domestic intelligence agency, the Federal Security Service, or the FSB is "most likely to have targeted Yevgeny Prigozhin's plane."

Former MI6 head Richard Dearlove told the Telegraph that Prigozhin's death was "unsurprising."

"I'm sure it'll be presented as an accident and there will be an element of doubt, but everyone in the West will come to the same conclusion-that this is Putin's revenge on people who challenge his power base," he added.

The Russian Federal Air Transport Agency announced late Wednesday that an Embraer-135 aircraft crashed in Russia's Tver region while flying from Moscow to St. Petersburg, killing all 10 passengers on board, including three crew members.

The agency later released a list of the names of those aboard the aircraft, which included Prigozhin, Wagner co-founder Dmitry Utkin, and other Wagner personnel.

The agency launched investigations into the incident, while Russia's Investigative Committee said in a statement on Telegram that it opened a criminal case on the basis of "violation of traffic safety rules and operation of air transport."

Prigozhin made headlines in June when he launched an "armed rebellion" against the Russian leadership before quickly aborting it after a deal brokered by Belarusian President Alexander Lukashenko.