Sydney man Peter Dundas Walbran, jailed in 2012 for the rape and molestation of Indonesian boys, has been detained after he was found teaching at a school in north-eastern Thailand.

The Fairfax Media reported that police turned up at Walbran’s apartment on Wednesday, when he was about to leave for school, with a search warrant on suspicion that he could be possessing child pornography. According to the police, the former head of the Australian International School in Jakarta was seen several times since Monday with children from the neighbourhood.

"We saw Walbran take a boy from the apartment to a shop on (the) back of his motorbike," Fairfax Media quoted a police investigator as saying. "We are investigating."

Walbran has been on Interpol’s wanted list since 2007 and he was extradited to Indonesia from Australia in 2011 following the rape charges. In 2007, he was charged with raping three male students after promising them money, Indonesian police special crimes official had said.

The effectiveness of Australia’s National Child Offender Register has come under questions after the discovery. The fact that Walbran could once again get back to teaching children in Asia after being deported back to Australia from Indonesia last year has clouded the efficacy of the body.

Teachers at the Narinukun International School are worried about the impact the revelations would have on the students and fear that parents might withdraw their children from the school after learning the news.

Walbran’s move was being monitored by undercover agents for days from an apartment adjacent to the one in which Walbran was staying for months. A Thai man who lived with Walbran in his apartment is expected to be questioned by police.

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