An Indonesian court has given a 20-year jail sentence to an Indonesian woman accused of killing a former classmate at an Australian school with cyanide-laced coffee, in a trial that was broadcast live and became a national spectacle.

The Central Jakarta District Court found Jessica Kumala Wongso guilty on Thursday of murdering Wayan Mirna Salihin at an upmarket Jakarta cafe in January. Salihin collapsed and died after sipping iced coffee at the cafe.

The two had been classmates at Billy Blue College of Design in Australia.

The court said Wongso was angry that Salihin had suggested she break up with a troublesome boyfriend.

Wongso's lawyers said they would appeal the verdict.