A teenage nephew has bitterly accused Sylvester Stallone of being to blame for the death of his son Sage.

In messages posted on Facebook, Edd Filiti claimed the Hollywood star could not be bothered to return Sage’s phone call wishing him happy birthday on July 6 — and that sent him over the edge.

Reports also suggest that Sage had been banned from entering his father’s home and had been “cut out” of his life. Sage, 36, was found dead in his Los Angeles apartment last Friday, a week after Stallone’s 66th birthday.

He is feared to have taken an overdose of prescription drugs, which were found at the scene. Autopsy results will take up to six weeks. On his Facebook page Filiti, 18, addressed the Rambo star’s third wife Jennifer Flavin, saying: “What did he do wrong, say happy birthday? Neither you or he [Stallone] could return a phone call, which is all he wanted, his father.

“I know you don’t care what happened, but you’ll care when you’re squirming under the burning magnifying glass of public opinion. You people make me sick.”

Father and son had a troubled relationship and Sage once admitted that when he starred alongside his father in the 1990 drama Rocky V he actually meant the lines: “You never spent time with me! You never spent time with my mother!”

According to a source quoted by the US showbusiness website Celebuzz: “Sage was not allowed in his father’s home and he admitted to other family members of his devastation that he’d seemingly been cut out of his father’s life.”

Sage was also reportedly experiencing financial problems at his two film production companies.

His cousin Filiti is the son of Stallone’s half-sister Toni Ann. On Facebook, he added: “Jennifer Flavin, you won. You tore this family apart and got your trophy, Congrats!

“Like you told my family, ‘I’m Sly’s family now, he doesn’t need you any more.’ Let’s see how much he needs you after this.”

However, the comments had been removed from Facebook and Filiti apologised. He said: “I made a mistake. It is a very emotional time and I vented my feelings. I was feeling raw and emotional and I never meant for my feeling to become public. I never meant to insult my uncle.

“I have my own issues with him, but that should never be said on Facebook.”

Los Angeles assistant coroner Ed Winter also denied reports that Sage was living in squalor surrounded by rubbish.

He said: “It seemed to be a typical male messiness. Mr Stallone did have a housekeeper.”