A high school said it is educating its students after "appalling" homophobic graffiti was daubed across a rainbow pride flag projected onto a classroom whiteboard.
Broadland High School in Hoveton said the graffiti, which told gay people to "die" and used abusive slurs, was "completely out of line with our standards and expectations".
In a separate incident a pupil was also filmed making abusive comments about gay and transgender people.
In an email to this newspaper, one member of the school community said they believed the behaviour constituted a "hate crime" and criticised the school for "failing to take appropriate action".
However, Broadland High said it has "unequivocally condemned" both incidents and said it operates a "zero-tolerance policy" towards prejudice of any kind.
A spokesperson said: "We have robust reporting reporting in place to ensure everyone's safety and wellbeing, and so were made aware of an incident on Tuesday which was filmed and photographed and was completely out of line with our standards and expectations.
"We took immediate action to deal with the situation and to implement appropriate sanctions for the small number of students involved.
"This will include providing additional education around these issues and actively informing the appropriate authorities.
"We pride ourselves on being an inclusive, open and accepting school community."
A school community member, who did not want to be named, said: "The school has been passive in response to this, with those who filmed it being asked to remove the content so it cannot be shared.
"I personally believe this is appalling and terrifying for the LGBT+ community."
In response, the school said it had asked pupils to voluntarily remove the content from the phones. It also said it has dedicated student safeguarding ambassadors who help to celebrate diversity and raise awareness of important issues.
It added: "We are currently in the process of expanding and deepening our curriculum to best reflect and support the entire student body, as well as educating them on the importance and value of diversity and inclusivity."
The government has mandated that all schools must teach sex and relationships education as part of their curriculum by June 2021.
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