Chih Chen abused 26 teenage girls in the Philippines over 25 trips to the country between May 2010 and June 2017.

He amassed more than 9000 pictures and videos of his victims, aged between 13 and 17, as well as of other children being abused.

Chen paid some of the girls he raped and abused, sent them graphic messages and encouraged them to find him new victims, including their younger siblings.

Some of the children appeared in pain and covered their eyes as the abuse was recorded. One of Chen's victims was abused while sleeping

When another victim said she did not want to be filmed, Chen said "I don't like sex without video".

The 52-year-old worked as a flight attendant throughout the abuse. He lost his job after being charged.

Chen was jailed in the County Court of Victoria on Monday for a maximum of 18 years and six months.

He previously pleaded guilty to 35 sexual crimes against children overseas, including producing child pornography, procuring children to engage in sexual activity, and persistent sexual abuse of and sexual intercourse with a child.

Judge Michael Cahill described the abuse as "prolific and protracted".

"You expressed a deep sexual interest in 12-to-14-year-old girls. At times you referred to girls as daddy's little girl," he said.

"When one girl told you she was 14, you replied, 'only 14 not 12'.

"You paid the girls modest sums of money which were no doubt large in their eyes for sex."

Chen must serve 14 years of his sentence before being eligible for release on parole.

He has already spent 150 days in pre-sentence detention.

Australian Associated Press