It had been reported that an unidentified Nigerian billionaire paid Cambridge Analytica $2 million to dig up dirt on Buhari ahead of the 2015 elections.
Cambridge Analytica is a UK-based political consulting firm which allegedly hacked President Muhammadu Buhari's records ahead of the 2015 elections.
The company was alleged to have hacked into Buhari's medical and financial records before the election.
Last week, the BBC had reported that an unidentified Nigerian billionaire paid Cambridge Analytica $2 million to carry out the alleged act.
The mystery billionaire was reportedly loyal to former president Goodluck Jonathan, who was seeking a re-election at the time. The Jonathan camp allegedly asked the firm to dig up implicating information about Buhari, with the goal of using it to nail him.
On Tuesday, March 27, 2018, the Jerusalem Post quoted a whistle-blower, Christopher Wylie to have told a UK parliamentary committee that Cambridge Analytica's parent company SCL Elections worked with Black Cube to hack Buhari.
"Wylie was quoted as saying; The company (Cambridge Analytica) utilised the services of an Israeli private intelligence firm, Black Cube.
"Black Cube on the Nigeria campaign was engaged to hack the now-President Buhari to get access to his medical records and private emails."
But Black Cube reportedly dismissed the whistle-blower's testimony, describing it as "flagrant lie."
"Whilst we are flattered that we are seemingly being connected with every international incident that occurs, we will state that Chris Wylie's testimony is a flagrant lie," the firm was quoted as saying.
It added that it will investigate Wylie's claims to "reveal the truth and the motive" behind them, and will also "launch a massive defamation suit against any entity that we will find involved, including Christopher Wylie, SCL or Cambridge Analytical, for any pound they still have or don’t have."
Black Cube also reiterated that neither it nor its affiliates and subsidiaries worked for SCL or Cambridge Analytica, or ever operated in Nigeria or on any Nigerian-connected project.