Hong Kong police are investigating an allegation that a four-year-old boy was indecently assaulted at an international school in Stanley, with the institution saying its security footage showed “no evidence of any wrongdoing” on the day of the suspected incident.

A source said on Wednesday that the International Montessori School kindergarten pupil complained to his family that his buttocks were sore on April 17 after his mother picked him up from school.

His father, who suspected that the child had been indecently assaulted, took the boy to Gleneagles Hospital in Wong Chuk Hang for a medical examination and reported the matter to police.

The insider said the medical examination found redness around the boy’s buttocks.

The source said police had classified the case as “indecent assault of a male under 16”, with the Western district investigation team tasked with following up.

In a statement on Thursday, the International Montessori School said it had reviewed records and closed-circuit television footage after learning of the allegation.

“We can confirm that this video footage from that day shows no evidence of any wrongdoing and that there was no evidence of any periods when the child was left unaccounted for,” it said.

The school added that police had informed it that “at this stage, no evidence has yet come to light of an assault on school grounds”.

“And at this stage, there is no evidence to suggest risk to any other students at the school, or the involvement of any member of the school community in an alleged assault.”

The institution said it was continuing to fully cooperate with police investigations.

In an earlier letter sent to parents and seen by the South China Morning Post, school head Timothy Veale confirmed that police had approached the institution for help on April 20 in connection with an alleged incident.

He said the school had been fully cooperating with the investigation.

“To our understanding, whether the alleged incident did happen on school premises is yet to be determined by police,” he said.

Veale also said the school was instructed not to disclose further details at this stage to avoid hindering police inquiries.

“We are certain that the matter is now in the good hands of the police and pending the result of the police investigation, they have advised us that any rumours will be detrimental to the police’s investigation,” Veale added.

The school said the safety and welfare of students remained its highest priority.

It said that prospective employees underwent criminal record and reference checks, in addition to being required to complete child protection training.