Brittany Murphy

The husband of actress Brittany Murphy has been found dead just five months after the death of his wife, according to reports.

The Los Angeles Times says British-born Simon Monjack, a screenwriter, died from unknown causes at his Hollywood Hills home.

LA Police Sergeant Louie Lozano told the newspaper that detectives were investigating at the scene.

Simon Monjack with wife Brittany Murphy.

It followed an emergency 911 call about 9.30pm Sunday (Los Angeles time) for an "unspecified medical aid request", LA fire department spokesman Brian Humphrey said.

The department sent staff to the scene to provide "medical services" to Monjack, but he was pronounced dead.

Celebrity website TMZ reported Murphy's mother, Sharon, found Monjack unconscious in the master bedroom.

Murphy, 32, who died of cardiac arrest in December, was ruled by the LA county coroner in February to have died of pneumonia, complicated by an iron deficiency, anaemia and "multiple drug intoxication".

The death was ruled an accident.

Among her best-known roles were Clueless, Girl, Interrupted and 8 Mile, while she also vocied Luanne Platter in popular animated TV show King of the Hill.

Murphy and Monjack married in a private ceremony in May 2007.