The 36-year-old son of Sylvester Stallone has been found dead, leaving the actor grief-stricken, his publicist said.

Details surrounding the death of Sage Stallone were not immediately available.

"Sylvester Stallone is devastated and grief-stricken over the sudden loss of his son," publicist Michelle Bega said in a statement.

"His compassion and thoughts are with Sage's mother, Sasha."

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Los Angeles police said they were dispatched to investigate a death at a home on Mulholland Terrace but could not confirm the person's identity or offer details.

Coroner's officials also said they were in the initial investigative stages.

Sage Moonblood Stallone was the oldest of Sylvester Stallone's children and co-starred with his father in two films.

"Sage was a very talented and wonderful young man, his loss will be felt forever," Ms Bega said.

He was the first of two sons Stallone had with first wife Sasha Czack.

Sage Stallone made his acting debut in 1990's Rocky V and also appeared with his father in 1996's Daylight. He also directed the 2006 short Vic, which was screened at the Palm Springs Film Festival.