British newspaper the News of the World quoted an unnamed FIFA official as saying that the body would launch an investigation because Australian midfielder Tim Cahill had made a wager with his teammates that he would score his country's first goal in World Cup history.

"I very much doubt the seriousness of this article," FIFA's head of communications Markus Siegler said at a daily briefing Sunday.

"This cannot be considered as institutionalised betting... That is the relevant difference."

Siegler said all players, officials and members of the FIFA Executive Committee at the World Cup had signed a charter in which they undertook to follow rules concerning issues such as doping and betting.

But he said bets made between players of the same team would only become a problem if they were "professionally organised".

Australia midfielder Tim Cahill admitted after the 3-1 defeat of Japan that his team-mates Lucas Neill and Archie Thompson bet on him to score the Socceroos' first ever goal in the World Cup finals.

Cahill, who plays for English Premiership side Everton, told Australian paper the Herald Sun: "They both backed me to score.

"That's why when I got the first goal I ran straight to them."

Australia captain Mark Viduka had said that the players were "taking bets on who was going to be the first to score."

He added: "Spider (reserve goalkeeper Zeljko Kalac) was the bookmaker."

The unnamed FIFA official told the News of the World that the charter signed by the players "includes internal betting within the players of any team, which is also strictly not allowed.

"The committee has made it very clear that no betting in any form should be taking place and they will investigate any case thoroughly."

Australia were taking on reigning champions Brazil in their second World Cup match on Sunday.