BALI, Indonesia (Reuters) - An Indonesian court sentenced a young Australian beauty therapist to 20 years in jail on Friday for smuggling marijuana into the holiday island of Bali in a verdict that could put a strain on ties.

Lawyers for Schapelle Corby, 27, said they would appeal the ruling, which triggered outrage from her family. Australian callers to radio stations in the country urged an end to aid to the world's most populous Muslim nation.

"The panel of judges declares the defendant legally and convincingly guilty of the crime of illegal importation of narcotics," chief judge Linton Sirait told a hearing that was watched live in Australia.

As soon as Sirait read the verdict, Corby's mother, Rosleigh Rose, shouted at the three judges on the panel: "Liar, liar. Honey, we are going to take you home."

Wearing pink trousers and a black blouse, an emotional Corby turned to her mother and pleaded with her to calm down. "Mum, stop, it's okay," she cried.

Standing for the verdict, Corby kept mouthing the word "20" in Indonesian, clearly stunned by the sentence.

Prosecutors had demanded life in jail for Corby, who has argued the 4.1 kg (9 lb) of drugs found by Bali airport officials in her unlocked bag last year were planted.