A teacher has been suspended and their school forced to apologise after a caricature of the Prophet Mohammed was shown in class, sparking a protest from parents.
Dozens of people gathered outside Batley Grammar School in West Yorkshire on Thursday morning to demonstrate following reports a member of staff had shown pupils the image during a religious studies lesson.
Depictions of the Prophet Mohammed are considered deeply offensive in the Muslim faith.
One parent at the school says the cartoon was taken from Charlie Hebdo, the French satirical magazine that was attacked in 2015 by Islamist terrorists who killed 12 people in Paris.
The caricature was shown to students in a lesson on 22 March, according to a letter to parents seen by Sky News.
School leaders were forced to apologise, admitting the image was "totally inappropriate".
Head teacher Gary Kibble said: "The school unequivocally apologises for using a totally inappropriate image in a recent religious studies lesson. It should not have been used.
"A member of staff has also relayed their most sincere apologies. We have immediately withdrawn teaching on this part of the course and we are reviewing how we go forward with the support of all our communities represented in our school.
"It is important for children to learn about faiths and beliefs, but this must be done in a respectful, sensitive way.
"A member of staff has been suspended pending an independent formal investigation."
He added: "The school is working closely with our governing body and community leaders to help us resolve this situation and we continue to do so."
On Thursday, people gathered outside the school to demand the resignation of the teacher involved.
Video footage posted on social media shows men wearing masks crowding around the school gate.
A police officer is seen reading a statement from the school as protesters shout that they want the member of staff "sacked".
The letter to parents reads: "The school would like to thank the parents who contacted us on Monday 22 March highlighting concerns with a resource used in an RS lesson that day.
"Upon investigation, it was clear that the resource used in the lesson was completely inappropriate and had the capacity to cause great offence to members of our school community, for which we would like to offer sincere and full apology."
In a letter addressed to Mr Kibble and shared online, founder of Batley-based charity Purpose Of Life, Mohammad Sajad Hussain, said he was "deeply hurt" by the "insulting caricatures of our beloved Prophet Mohammed".
Yunus Lunat, an executive member of the Indian Muslim Welfare Society in Batley, told Sky News he thinks the teacher "went off script" and was trying to "provoke".
"They talk about freedom of expression, but I question what freedom of expression has to do with an RE lesson," he said.
"You will never see an image of the Prophet Mohammed in our mosque, in any mosque in the world. It’s not acceptable."
He added: "That gives you some sense of understating as to why these cartoons cause aggravation."
Mr Lunat said he also fears the debate may be "hijacked" by people not directly related to the school.
West Yorkshire Police said it was called to the protest at around 7.30am on Thursday.
A police spokesman said the school road had been closed for a short time, no arrests were made and no fines were issued.
The National Secular Society called the demonstration an "attempt to impose an Islamic blasphemy taboo on a school".
The society’s chief executive Stephen Evans said: "Teachers must have a reasonable degree of freedom to explore sensitive subjects and enable students to think critically about them.
"And the school’s weak response will fuel a climate of censorship, which is brought on by attempts to force society as a whole to accommodate unreasonable and reactionary religious views."