FIFA banned Suarez for nine Uruguay matches -- and from all football activity for four months -- after he bit Italy defender Girogio Chiellini in a World Cup group game.
It is the third time the Liverpool striker has been banned for biting an opponent. He had told FIFA's disciplinary panel that he did not deliberately bite Chiellini, writing in Spanish that "in no way it happened how you have described, as a bite or intent to bite."
Ron Jans, who signed Suarez for FC Groningen from Nacional in 2006, recalled numerous clashes with Suarez during the time in which they worked together.
He said the player had hurled an umbrella at him after being substituted, and told The Mirror: "I spoke to Brendan Rodgers about Luis, and I did tell him the player could be erratic but also that he was a great talent.
"In the early days, we had collisions at the training ground. He turned up in Holland thinking he could walk straight into the first team, but I put him in the reserves.
"Why? Because he was doing nothing in training. He was not fit, and I told him that. He hated it, but did get the message.
"One day I substituted him. It was raining, and he grabbed an umbrella and threw it at me in temper."
He said that "of course players have tantrums" but condemned Suarez for what he did at the World Cup, saying: "Biting? That's disgusting.
"This really, really hurts me. I have massive respect for Suarez the player. I always have had, from the day we brought him from South America to Holland. Yet biting cannot be tolerated in football or in life.
"I still like and care for Luis Suarez. He is a nice boy, honestly, but even I admit that he needed to be punished for this.
"If FIFA had not acted on this, it would have given total freedom to every player to do whatever they want on a football pitch."
Jans became the latest football figure to say he believed Suarez needed professional help, echoing comments made by Kenny Dalglish, who signed the striker for Liverpool in 2011.
"I think even Luis does not understand his own actions," he said. "But it is up to Luis now. Only he has the key for his own behaviour problems."
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