(CNN) -

Convicted Singaporean match-fixer Wilson Raj Perumal is categorically denying a story published by German weekly Der Spiegel alleging that the Cameroon team was involved in fixing a World Cup game in Brazil.

The Cameroon federation -- known as FECAFOOT -- has pledged to investigate Der Spiegel's allegations, which focused on the national side's second Group A game against Croatia -- purportedly based on an interview with Perumal.

"Contrary to the 'revelations' published by the German weekly Der Spiegel that were picked up by news outlets worldwide, I did not predict the result of the Cameroon vs. Croatia match played on June 18, 2014," said Perumal in a statement published online.

"The Facebook chat with the Der Spiegel journalist took place a few days after the match -- June 21 -- as confirmed by my Facebook log, and was but an informal assessment of the behavior of the Cameroon team at the Brazil 2014 World Cup after they had played two of their three group stage matches, including the one with Croatia."

CNN has been sent screen grabs of two Facebook conversations between Perumal and the journalist, Rafael Buschmann, by the fixer's representative.

The first is dated the June 21 and the second is dated the June 26 -- in other words after the Croatia game -- where Perumal talks of "five to seven black sheeps," and "seven rotten apples" within the Cameroon team, adding "in my opinion they fixed all three matches."

Perumal's Facebook account does not show public updates, so CNN was unable to independently verify those exchanges.

"At no time did I make reference to four goals being scored or to a red card being issued," Perumal said.

"At no time did I suggest that I had any way of corroborating or substantiating what was meant to be an educated guess based on my extensive match-fixing experience," added Perumal, who was arrested in Helsinki in 2011 and sentenced to two years in prison for fixing games in Rovaniemi, northern Finland.

"Last but not least: at no time was I informed by the Der Spiegel journalist that our chat was going to end up in the German publication."

The Der Spiegel journalist, Rafael Buschmann, told CNN that the publication was confident in its reporting of the story.

"We firmly stand by our assertion that Mr. Perumal wrote in a Facebook chat with Der Spiegel some hours before the World Cup match Croatia vs. Cameroon, that the result of the match will be a 4-0 victory for Croatia and that a player of Cameroon will get a red card in the first half," Buschmann said.

That alleged prediction largely came true.

Midfielder Alex Song was red-carded during the game for lashing out at Croatia striker Mario Mandzukic, who scored twice in a 4-0 victory along with goals from Ivica Olic and Ivan Perisic.

CNN contacted Song's agent but he was not immediately available for comment.

Now living in Hungary, Perumal recently published a book -- "Kelong Kings" -- about his involvement in illegal match fixing, which was written in conjunction with investigative journalists Alessandro Righi and Emanuele Piano.

"I apologize to the Cameroon FA and to its fans if I inadvertently offended them; it was not my intention," said Perumal. "I strongly believe that Der Spiegel should also do the same since they placed words in my mouth that I did not utter."

"Kelong Kings" examines three decades of match-fixing efforts, including World Cup qualifiers, Olympic matches and the 2010 World Cup.

"I am now back in Hungary where I have testified against my former associates in a local match-fixing trial," said Perumal.

" 'Kelong Kings' is an honest account of what my life has been like until today.

"I have now turned a new leaf and wish to put my expertise at the disposal of those willing to truly fight the scourge of match-fixing.

"When the time is ripe I will share what I know with FIFA and UEFA, but I will not accept that my statements be manipulated at the detriment of others."

A FIFA spokesperson told reporters Tuesday that football's governing body could not comment on whether an investigation was underway on the alleged manipulation of the Cameroon-Croatia match.

FECAFOOT said in a statement Monday that "in 55 years of existence, it has never been sanctioned for, involved in, or even linked to match fixing or any fraud of any kind."