Sky News: The man who founded McAfee technology in the late 1980s claimed the rivals had “spiked something” that he consumed and he has now made a threat that they “better be gone”.
He spoke of the alleged death plot on Twitter along with two photos of him connected up to tubes and lying on a hospital bed.
McAfee wrote: “I apologise for my three day absence but I was unconscious for two days at the Vidant Medical Center in North Carolina and just woke up.
“My enemies (managed) to spike something that i ingested. However, I am more difficult to kill than anyone can possibly imagine. I am back.”
He added: “And for those who did this – you will soon understand the true meaning of wrath. I know exactly who you are. You had better be gone.”
The 72-year-old British-born tech executive founded McAfee Associates in 1987. He eventually resigned from the company in 1994.
He sold his shares and reportedly made $100m (£75m).
In November 2012, Belize police named McAfee as a “person of interest” in connection with the murder of Gregory Viant Faull, an American ex-pat who was a neighbour of McAfee.
Mr Faull was found dead after being shot. McAfee has denied any involvement in the killing.
McAfee was then arrested in Guatemala by immigration officials for entering the country illegally.