Hackett says he's working on his 'issues'

Three-time Olympic gold medallist Grant Hackett says he's working on his issues after an altercation with a fellow passenger on a flight from Adelaide to Melbourne.

The passenger says Hackett reached through the gap between seats and grabbed his chest and tweaked his nipple in what he described as a "sexual assault".

Collingwood AFL chief executive Gary Pert, who sat across the aisle from Hackett on Sunday afternoon's flight, says the swimmer wasn't aggressive but appeared to be affected by alcohol to the point of being "incapacitated".

The incident was reportedly sparked by the passenger in front of Hackett reclining his seat.

Hackett offered an unreserved apology on Monday and admitted he "stuffed up" again.

The Olympian previously found himself under scrutiny after he trashed the Melbourne apartment he shared with his former wife Candice Alley in 2011.

Three years later he went to a US rehabilitation centre for treatment for sleeping pill addiction after he was photographed partially dressed searching for his young son at a hotel.