WARNING: This story contains graphic content that some readers may find upsetting

A schoolboy has told a court he was forced face-down onto a bed by teammates, his pants pulled down and sexually assaulted with a carrot while on an international rugby tour representing Perth's prestigious Trinity College

Key points: The boy says he was sexually assaulted on a rugby team trip in 2017

The boy says he was sexually assaulted on a rugby team trip in 2017 Two teachers who supervised the trip are on trial

Two teachers who supervised the trip are on trial They are charged with failing to report suspected child sexual abuse

The alleged incident was outlined by the victim, who yesterday gave evidence in the Perth Magistrates Court trial of two of the teachers who supervised the tour and have been charged under mandatory reporting laws.

Ian Francis Hailes and Anthony Paul Webb have both pleaded not guilty to failing to report suspected child sexual abuse.

Former Trinity College teacher Anthony Paul Webb is charged with failing to report alleged sexual abuse. ( ABC News: Hugh Sando )

They are the only people to be charged as a result of the alleged incident at a Japanese hotel on the outskirts of Tokyo in April 2017.

Trinity College is a Catholic boys' school on the banks of the Swan River and is jointly governed by Catholic Education WA and Edmund Rice Education Australia, which oversees Christian Brothers schools throughout Australia, including St Kevin's in Melbourne.

Alleged sexual assault followed bullying

The victim — whose identity has been suppressed and is being referred to as AB — told his story via video link, explaining how he had been repeatedly bullied on the 10-day trip.

Trinity College charges $15,140 per student per year for years seven to 12, not including other fees. ( ABC News: Hugh Sando )

But the most "traumatic event", for which he is still getting counselling, happened as he was relaxing on a tatami floor mattress one evening, chatting to a fellow student and playing games on his phone.

AB told the court a group of about 10 boys burst into the room, flipped him over and pulled down his pants and "aggressively" and "rapidly" forced the carrot into him.

He said he was very embarrassed by the incident, so afterwards he tried to ignore other people and force himself to go to sleep.

"I didn't want it to escalate into a big thing with everyone talking about," he said.

Allegations raised at meeting run by teachers

He said he raised the incident with teachers at what was known as a "fines session", a mealtime meeting run by Mr Hailes and Mr Webb where student misdemeanours would be raised and those responsible would pay a 100-yen fine into a dish.

Former Trinity College teacher Ian Francis Hailes warned the group to stop harassing AB, the court was told. ( ABC News: Hugh Sando )

He said he told the meeting in the hotel cafeteria that "you know what went on" and wanted the perpetrators to acknowledge the incident, pay a fine and then stop talking about it.

He told the court that he had mentioned to both teachers what had happened, with Mr Webb later asking him whether he wanted the issue followed up, to which he replied "no".

When he returned to his room from the cafeteria, some of the boys began to call him a "snitch".

The boys were on a sporting trip to play rugby in Japan. ( ABC News: Hugh Sando )

Students speak of culture of bullying at school

Year 10, 11 and 12 students took part in the 10-day tour to Japan, where they played rugby against Japanese teams and also enjoyed some sightseeing and shopping.

One of the younger students on tour gave evidence about a culture of bullying of younger students by the "alpha male" older students, including "fight clubs", threats that they would be the next to "get the carrot" and name calling.

He told the court that he witnessed AB's alleged assault — describing what he saw as "excessive force and malicious intent".

He said he helped AB out and asked him if he was OK afterwards.

But he said he was scared and intimidated by the alleged perpetrators and didn't want the same thing to happen to him.

"I am inferior to them," he said.

"The intimidation shocks you into a quietness."

Another of the students who gave evidence said that terms like "carrot boy" were being bandied around and that bullying was part of the Trinity Rugby Club's culture.

They both said Mr Hailes had warned the tour group to stop harassing AB.

AB said he never spoke about the incident again until he was questioned by a senior staff member about five months after they returned to Australia.

Not long after, a mandatory report was made.

The trial before Magistrate Evan Shackleton is continuing.