SINGAPORE - For more than 15 years, convicted Australian paedophile Boris Kunsevitsky documented his sexual abuse of 47 children, including five in Singapore, on videos and in photographs that he stored in an online file entitled "jailbait".

The term is slang for someone who is below the legal age of consent for sexual activity, and Kunsevitsky had produced more than 1,000 photographs or videos of child pornography.

His crimes were detailed in court documents the Australian authorities gave to The Straits Times.

Kunsevitsky, 53, had pleaded guilty in a Melbourne Court last week (May 21) to 59 counts relating to child sex abuse and child pornography.

He was based in Singapore when he committed most of his crimes against children in South-east Asia and Australia, said the documents.

One of his earliest crimes is the sexual abuse of a boy in Singapore between September 2002 and August 2003.

The boy's age then is estimated to be between 12 and 14.

He had sex with the boy in his home here and photographed some of the sexual acts.

He also took multiple pictures of the boy engaged in "pornographic posing"or activity on other occasions, said Australian prosecutor Krista Breckweg in court last Monday (May 20).

The boy was also photographed watching "child exploitation material" on a laptop and viewing close-up images of his erect penis, she added.

The boy was one of five children Kunsevitsky abused in Singapore. The rest of his victims lived in Indonesia, Australia and the Philippines.

In Indonesia, he abused a 12-year-old boy between August 2002 and December 2002.

Images found by the police showed the boy eating takeaway food from McDonald's and then performing oral sex on Kunsevitsky.

In the Philippines, where most of his victims lived, he directed boys to engage in sexual acts with each other and he would document them.

In Australia, he had a sexual relationship with a boy aged below 16 from January 2004 to October 2005.

He had met the youth in an online chatroom for teenagers, and told him he was 19. They had sex multiple times.

On one occasion, he met the boy in the home of his parents-in-law where he set up a tripod and a video recorder in front of the bed.

In another incident, he showed the teenager 14 pictures of boys in Asia. "He told him he had sex with them and they were all 12 to 14, because any younger and he would be taking advantage of them," Ms Breckweg told the court.

The court also heard that the German police had referred Kunsevitsky's case to their Australian counterparts in 2008, but the Australian victim involved was identified only in 2016.

Kunsevitsky was arrested on Sept 4, 2017, when he returned to Australia.

When questioned by the police at the airport about images on his phone showing him having sex with a child, he said he never engaged in sexual acts with children, Ms Breckweg said.

But the police found more evidence of his crimes in multiple electronic devices among his belongings that were shipped from Singapore.

Kunsevitsky has since been dubbed one of Australia's worst sex offenders. He is in remand in Australia, awaiting sentencing.