LONDON, United Kingdom — A retired English teacher was jailed for at least 16 years on Wednesday for what his judge called an “appalling catalogue” of sex offences against children in Thailand and Britain.

Mark Frost, 70, admitted 45 sex offences against nine children in Thailand between 2009 and 2012 and two British pupils in the 1990s.

The offences including rape, sexual assault and inciting sexual activity with a child under 13. His victims were aged between 10 and 15.

At England’s Central Criminal Court in London, he was sentenced to serve 13 concurrent life sentences and will spend a minimum of 16 years in jail.

His crimes were “the most appalling catalogue of sexual abuse”, judge Mark Lucraft said.

“It is clear you have an obsession with sexually abusing young boys with evidence of planning and grooming.

“Your conduct towards each and every one of these victims is horrific and deeply disturbing.”

He added Frost’s offending was “truly shocking” and that he was someone who will continue to pose a risk to children.

The court heard how Frost raped impoverished Asian boys and encouraged them to engage in sex acts after grooming them with cash and sweets.

“The harrowing evidence presented by the prosecution in this case outlined the suffering that Mark Frost caused to his victims,” said Ruona Iguyovwe, from the state’s Crown Prosecution Service.

“Over many years, Frost repeatedly exploited vulnerable young victims, both in the UK and in Thailand, for his own sexual gratification.

“His offending has caused severe psychological harm to all of the children he abused, many of whom are now old enough to realise the enormity of what happened to them.”

The National Society for the Prevention of Cruelty to Children (NSPCC) urged other potential victims to come forward.

“Mark Frost’s vile campaign of sickening child abuse spanned over quarter of a century in the UK and abroad, and today’s sentence will likely see him spending the rest of his days behind bars,” a spokesman said.

“Frost was a prolific and dangerous paedophile who worked as a teacher and Scout leader for decades. We hope that anyone who suffered can now find the courage to speak out.” CBB