Demi Moore suffered convulsions after smoking an undisclosed substance, according to a tape of an emergency call from last Monday. The 49-year-old actress is described as "semi-conscious, barely" in the recording, which was released by Los Angeles fire officials, the Telegraph writes.

The tape captures the few minutes it took paramedics to arrive as friends gathered round the collapsed star.

In November, she ended her marriage to actor Ashton Kutcher, 33.

In the emergency call, a woman is asked by operators: "Is she [Moore] breathing normal?"

"No, not so normal," the woman says. "More kind of shaking, convulsing, burning up."

When the dispatcher asks if Moore has ingested or smoked any substance, the woman replies: "She smoked something. It's not marijuana but it is similar to incense."

But the full answer was redacted on the advice of the city attorney's office, citing federal medical privacy rules.

"She's been having some issues lately with some other stuff," says the woman.

Asked by the operator if this has happened before, the female voice says: "There's been some stuff recently that we're all just finding out."

By the end of the call, Moore's condition appears to improve.

A man tells the operator: "She seems to have calmed down now. She's speaking."

The actress's publicist has previously said Moore suffered from exhaustion.

Her split from Kutchner, whom she married in 2005, followed allegations of his infidelity.

Moore was formerly married to actor Bruce Willis, with whom she had three daughters Rumer, Scout and Tallulah Belle.