Vladimir Putin's right-hand man, security adviser Nikolai Patrushev, is suspected of being behind the assassination of Wagner's mercenary boss Yevgeny Prigozhin earlier this year.
Prigozhin died in an air accident when his private plane crashed on the outskirts of Moscow in August this year.
US media sources revealed that Putin's security adviser, Nikolai Patrushev, was allegedly behind the assassination plot.
According to an investigation launched by the Wall Street Journal after the death of Wagner's boss, Patrushev hid a "small explosive device" under the wing of Prigozhin's private jet before it left for St. Petersburg on August 23.
The paper quoted a former Russian intelligence officer as claiming that Patrushev "ordered his aide to proceed with the formation of an operation to eliminate Prigozhin".
Putin is said to have been "shown the [assassination] plans and did not object."
Kremlin spokesman Dmitry Peskov confirmed that Moscow was aware of the US newspaper's investigation, but declined to comment on the matter.
"We saw this material, but we would not like to comment on it," Peskov declared. "It is unlikely that such materials can be commented on," he added.
Sergei Markov, a pro-Kremlin political analyst, said the WSJ newspaper and the West wanted to "discredit" Patrushev by blaming Putin's security aide for Prigozhin's death.
Prigozhin and nine others were killed on August 23 when the Wagner boss' Embraer Legacy 600 plane crashed on the outskirts of Moscow while en route to St Petersburg.