Zinedine Zidane's [Images] head-butt on Italy's [Images] Marco Materazzi during the World Cup final was apparently prompted by the latter's loose comment about the French captain's wife, the defender's agent said.

The Inter Milan player's agent Phil Smith on Wednesday gave the Italian's version of what happened.

Speaking to Sydney's Daily Telegraph, Smith said the altercation began when Materazzi grabbed the Frenchman's shirt, pinching his nipple.

"If you want my shirt so much, then you can "---" have it after the game," Zidane supposedly said.

`I'd rather have the shirt off your woman,' Materazzi was then said to have responded, referring to Zidane's wife Veronique.

This indecent remark was apparently too much for Zidane to take and he rammed his head into the chest of the Italian, an act for which he was sent off by the referee with 10 minutes left to go for the end of extra-time.

Earlier, when asked whether he had insulted Zidane's sister or mother, Materazzi on arriving in Italy had said, it was an "insult of the kind you will hear dozens of times and that just slips out on the ground".

But he denied calling the mercurial Frenchman a terrorist.

"I certainly didn't call him a terrorist; I am ignorant, I don't even know what an Islamic terrorist is," he said. "I certainly did not mention Zidane's mother; for me a mother is sacred."

The French player's agent said that the footballer's sharp reaction was provoked by a "very serious" comment made by the Italian defender.

Football world governing body FIFA has launched its own probe into the incident. Zidane has not said anything on the matter as yet.

According to a report on Brazilian television channel Globo, the former Real Madrid [Images] star's act in his last match before retiring may have been provoked by Materazzi calling his sister a prostitute.

'Fantastico', a programme on Globo, employed lip-reading experts who said footage of the incident showed the Italian twice insulted Zidane's sister.

The programme claimed Materazzi made the same comment twice before then using a "coarse word" at the French player.