Indonesia's Supreme Court overturned the acquittals of a Canadian administrator and a local colleague accused of sexually abusing pupils at a well-known international school, and increased their jail terms, officials said in Jakarta.

An appellate court in August last year quashed the 10-year sentences given to Neil Bantleman and Ferdinand Tjiong after they were convicted of sexually abusing kindergarten pupils at the Jakarta International School.

But a panel of Supreme Court judges reinstated the original verdicts and increased the jail terms to 11 years, court spokesperson Suhadi said.

"The verdict of the court of the first instance was correct and was based on sufficient evidence," said Suhadi said yesterday, adding that the decision was made on Wednesday.

Chandra Saptadji, a spokesperson for the South Jakarta Prosecutor's Office, said Tjiong was picked up early yesterday to serve his sentence, while Bantleman was yet to be found.

"His house was empty," Chandra said. "We are asking him to be cooperative."

The Canadian government was "deeply dismayed and shocked" by the court's decision, Foreign Affairs Minister Stephane Dion said.

'Many grave irregularities'

"This decision is unjust, given the many grave irregularities throughout the various proceedings in this case and the fact that all evidence presented by the defence has systematically been rejected," Dion said in Ottawa.

Despite Canada's repeated calls for due process, this case was not handled in a fair and transparent manner, he said.

"The outcome of this case has serious implications for Indonesia's reputation as a safe place for Canadians to work, travel and invest, as well as for Canada's long history of cooperation with Indonesia," Dion said.

United States Ambassador to Indonesia Robert O’Blake said, "We are shocked and disappointed by the decision."

"The international community continues to closely follow this case," O’Blake said. "The outcome of the legal process will impact international views about the rule of law in Indonesia."

The US government is a founding partner of the school, which is attended by children of diplomats, expatriates and members of the Indonesian political and business elites.

Parents of at least three kindergarten pupils at the private school, since renamed the Jakarta Intercultural School, came forward in 2014 with allegations of sexual abuse by members of the school's staff.

Bantleman and Tjiong have denied the allegations.

Their lawyers argued that the medical evidence presented by the children's parents was fabricated and money was the motive.

A US$125 million lawsuit filed by the parents against the school was thrown out last year by a Jakarta court.

- dpa