Billionaire adventurer Richard Branson has been dragged into the Amanda Knox murder case controversy after his tweet casting doubt on the conviction of the student and ex-boyfriend Rafaelle Sollecito.

The whole controversy started when Richard Branson wrote on his social media on December 18: "Questions need answering in Amanda Knox case, everyone deserves fair treatment & a fair trial https://www.injusticeinperugia.org/  #readbyrichard."

A lot of critics, however, pounced on the Virgin Airlines boss for his alleged bias without fully understanding the facts surrounding the Amanda Knox murder case.

User Netropy commented: "@richardbranson I am extremely surprised you would link to this website. It is Meredith who deserves justice. Did you consider her in this?"

Another wrote: "@richardbranson Mr. Branson, please imagine the victim was your daughter, then research what #amandaknox & Sollecito were found guilty of."

User Perugia Murder File wrote: "@richardbranson Please don't be had by a propaganda site. Hardly content there is true. There are causes far more worthy. #AmandaKnox."

The user added: "We have followed this case from the beginning. #AmandaKnox got a fair trial and the evidence against her is overwhelming."

But it's not all criticism as Richard Branson also found some supporters who praised his decision to take sides in the issue.

"Richard Branson, Thank you so much for speaking out for justice. This is huge and was the right thing to do. Merry Christmas," Michelle Moore, who is a friend to Amanda Knox, tweeted.

The website Ground Report noted that Richard Branson might have become the unwitting target of the haters of the American student who insist that the Amanda Knox murder case conviction was correct.

"The irony of the troll claims is that Knox and Sollecito's reputations as regular students of good character with no history of violence or antisocial behaviour were destroyed by PR spin that emanated from law enforcement in Perugia, starting the day after Meredith Kercher's body was discovered," the site said. "Their character assassination was completed by the tabloid media, led from Britain by the same newspapers that printed lies about Christopher Jefferies, the innocent retired teacher from Bristol, England."