It emerged this week that Aabar had sold back its 40 per cent stake in Mercedes' works team.
But Aabar continues to back Toro Rosso, Red Bull's second Formula One team, through its Spanish oil brand Cepsa.
And Germany's Sport Auto reports that Aabar has now bought part of the Faenza based squad.
"The (percentage) number (of the stake) is between 49 to 61 per cent," the magazine said.
Toro Rosso is yet to comment.