SINGAPORE - The man seen looking on in the background of a video as three St Hilda's Secondary students brawl is not a teacher, the school has clarified.

He is an intern with an external agency that the school had hired, said vice-principal Tan Yee Leng on Thursday (Sept 14) in response to queries from The Straits Times.

In the video that went viral online, two students confront a third boy, throwing punches at him and hurling vulgarities.

The man is seen watching the fight from near a door, but he does not appear to intervene.

St Hilda's said that the incident happened on Monday.

Miss Tan said the man "chanced upon the incident when walking along the corridor, and had called out to the students to stop the fight but they did not heed him".

"Since he is not one of our teachers, he would not have the training or authority to manage the situation," she said.

Miss Tan added that the students have been counselled and "appropriate disciplinary measures" have been taken.

The school is also working with the boys' parents to help them learn from the incident, Miss Tan said.

"We take all incidents of fighting seriously, and we are confident that our teachers will be able to manage and correct inappropriate behaviour," she added.