The attacking midfielder, who was nurtured in the Bucs academy, has repeatedly been linked with a move to Amakhosi since last season.
The Citizen source close to Mahlasela has revealed to the publication that Chiefs are still keen to sign the player, but Mahlasela prefers to move back to Pirates.
“They have spoken with him and Celtic are aware Chiefs want to sign him," the source said.
"The problem is that he (Mahlasela) wants to go back to Pirates because that is where he grew up," the source continued.
"I’m not sure if Pirates have spoken to him, but last time I heard about the Pirates move he (Mahlasela) said they are monitoring him,” the source concluded.
The 26-year-old, who joined Phunya Sele Sele on a three-year deal in 2015, has been one of the club's top performers this season.
He has made nine appearances in all competitions - scoring once in the process.