During Saturday's tea break in the England-Australia Ashes Test at the Melbourne Cricket Ground, Lee left Morgan battered and bruised as he pounded the Englishman with an over of short-pitched deliveries.
"As a former fast bowler I was appalled and outraged at what I witnessed," Hadlee said in a column written for Fairfax News.
The exhibition was organised after Lee challenged Morgan to face an over when the television interviewer questioned the courage of some England batsmen.
"This was a brain explosion of the highest order. It was a deliberate attempt to hit, injure, hurt and maim his opponent that I viewed as a form of grievous bodily harm or a human assault that could have proved fatal."
Morgan, 48, was hit four times on the body by the 37-year-old Lee who only retired from international cricket 17 months ago.
"If he was hit on the head or across the heart the result could have been devastating. Lee bowled only one ball at the wickets, and the other five were directed at the batman's middle to upper body and head.