The trial of an Australian man has begun in Indonesia on charges he sexually abused 16 girls on the tourist island of Bali in 2014 and 2015.

Robert Andrew Fiddes Ellis is being tried behind closed doors at Denpasar District Court.

Siti Sapura of the Center for Women and Children Protection and Empowerment said four girls aged 8 and 12 and another aged 17 who acted as intermediary testified at the first hearing Thursday.

The 69-year-old Ellis, who was arrested on Jan. 11, is charged under Indonesia's Child Protection Law, which carries a maximum sentence of 15 years in jail.

His lawyer, Benny Hariyono, denied the charges, saying Ellis touched their bottoms instead of genitals.