Media coverage by Zulu news programmes was more critical of paralympian Oscar Pistorius than other language groups, research company Media Tenor said on Thursday.

"[The tone] received from Zulu TV seemed to be a lot more critical at 82 percent compared to other TV news reports, thus moulding the public's perception that Pistorius was probably guilty," principal researcher Ludene Brown said in a statement.

Sotho news programmes were 30 percent critical of Pistorius and Afrikaans news was 29 percent critical of him.

"Many convicted killers do not get close to this level of negative coverage," said Brown.

"It is unprecedented."

Pistorius is accused of killing his model girlfriend Reeva Steenkamp in February last year.

Brown said the media likened Pistorius to fallen heroes such as philanderer Tiger Woods, murder accused OJ Simpson, and substance abuser Lance Armstrong, showing that "the media was already pillorying [him]".

Media Tenor said television coverage of Steenkamp skyrocketed after her death.

"Steenkamp was a lesser known model and TV personality prior to her death," co-researcher Minnette Nieuwoudt said.

"Her media presence skyrocketed after her untimely demise."

The only positive outcome of her murder was that domestic violence in South Africa was highlighted.

Nieuwoudt said 105,968 television reports on six news programmes were monitored last year in Media Tenor's research.

Percentages were based on news programmes in specific language groups.

Media Tenor said its data supported reports that Pistorius was given a trial by media.