An Indonesian court on Tuesday sentenced an Australian retiree to 15 years in prison for sexually abusing girls on the tourist island of Bali.

Robert Andrew Fiddes Ellis was arrested in January and accused of abusing 11 girls as young as 8. Some of the victims said Ellis gave them small amounts of money and gifts such as a bicycle in exchange for letting him bathe them.

Ellis admitted the offenses but in comments made to media last week he also defended his actions as harmless.

The Denpasar District Court found him guilty of violating Indonesia's Child Protection Law, and the panel of judges, led by Wayan Sukanila, also fined Ellis 2 billion rupiah ($153,000) or a further six months in prison if the fine wasn't paid.

"The defendant has been proven guilty of persuading children to perform obscene acts repeatedly," Sukanila said. "There are no excuses for the defendant's deeds."

The panel also said that Ellis had damaged the image of Bali's tourism industry.

His lawyer, Yanuar Nahak, said Ellis will appeal. He said the sentence was too heavy because Ellis confessed and promised not to reoffend.

Ellis came to Bali in 2013 on a five-year retirement visa. The case involves crimes committed in 2014 and 2015.