Ozzy Osbourne's final months were filmed for a documentary

Jack also told the Dail Mail's Weekend magazine that his father had finished an autobiography called Last Rites, which is due out later this year.

Jack, 39, did the interview before his father passed away and during the chat, he spoke about his work as a co-producer on an upcoming biopic about Ozzy.

He said: "Right now it'll take place over the Sabbath era and early 1980s. We're definitely going for a more adult rating for the film.

"This is by no means going to be a fluff piece. Right now we're going through a rewrite with Craig Borten, who wrote [Matthew McConaughey-starring] Dallas Buyers Club."

News of Ozzy's death was confirmed by his family in a statement, which read: "It is with more sadness than mere words can convey that we have to report that our beloved Ozzy Osbourne has passed away this morning. He was with his family and surrounded by love.

"We ask everyone to respect our family privacy at this time. Sharon, Jack, Kelly, Aimee and Louis."

It was later reported that Ozzy passed away at his home in Buckinghamshire and his family had flown in from Los Angeles to be with him.

A source told MailOnline: "[His passing was] unexpected to be this soon."

The insider added that daughters Aimee, 41, and Kelly, 40, had come from Los Angeles to be with their father and Jack had flown in from his home in Idaho to watch his father perform at his final Black Sabbath gig in Birmingham on July 5.

The source said: "Ozzy was always meant to come back to Britain to live in Buckinghamshire, it was where Sharon had spent so long preparing their family home for him. "There was much hope that he would be around for a lot longer than this but at one point there were fears they would not get him back from Los Angeles for the concert earlier this month.

"Kelly has been at the house a lot in the last week or so, so has Aimee. It is terribly sad for all of them, they really hoped he would be able to carry on for a bit longer. "But it's so lovely that he had his children around him during his last days."