Protests against LGBT lessons in schools have been hijacked by those with a “religious, extremist agenda” who are holding schools “under siege”, MPs have said, as the number of schools being targeted has grown.

Anderton Park primary school, in the Moseley area of Birmingham, has become the latest site of demonstrations against the teaching of LGBT rights, following similar protests at other schools in the city. On Friday, the last day before the half-term holiday, staff were forced to send children home after another protest. Earlier this week, protesters claimed 600 of the school’s 700 pupils were withdrawn by parents, a figure disputed by the school, which said more than half remained in attendance.

West Midlands police are investigating threatening emails and phone calls against the school’s headteacher, Sarah Hewitt-Clarkson, and allegations that mostly female LGBT activists were pelted with eggs by men wearing balaclavas as they placed heart-shaped messages and banners on the school fence.

Taking centre stage in the protest is 32-year-old Shakeel Afsar. For six weeks he has stood outside the school with a microphone, chanting with fellow campaigners: “Let kids be kids,” and “Our kids, our choice”. Other protesters have carried placards with the messages: “Adam and Eve, not Adam and Steve.” They have also demanded the resignation of Hewitt-Clarkson. Although the school does not teach No Outsiders, the programme that informs children about LGBT identities, it does share equality messages and books with pupils.

Afsar, whose daughter attends an Islamic school, went to Anderton Park as a child and has a niece and nephew who currently study there. He grew up in a heavily politicised household in which his father, Najib Afsar, the head of the Birmingham-based Jammu Kashmir Liberation Council (JKLC), would regularly give talks and organise protests against events in the disputed region.

The family has links with a number of local and national politicians and political aides, including the MP Roger Godsiff, who has criticised LGBT+ inclusive education. The family also runs a TV channel – Kashmir Broadcasting Corporation – which is currently off-air but has a website that regularly posts updates on the schools protests.

Najib Afsar, who has described Hewitt-Clarkson as a dictator, says he does not take part in the protests, but that his son has his full support.

“He has a working team of five people. I don’t participate in their activities, because that is their show and we don’t get involved in it,” he said.

However, he later revealed he had written to the school to ask to be appointed as a mediator. The school refused his request. He has also written to local and national politicians about the issue and said it was a boost to his son’s cause to have Godsiff, the Labour MP for Birmingham Hall Green, endorsing their views.

The protests have been met with anger from Labour’s Jess Phillips, the MP for Birmingham Yardley, who lives near the school, and said they were being organised by a group of “12 angry men”.

The MP Jess Phillips confronts Shakeel Afsar outside Anderton Park school. Photograph: BBC News

She recently confronted Shakeel Afsar at the school gates, accusing him of damaging the reputation of Birmingham’s “peaceful and loving” Muslim community.

She said: “It is hate preaching. The protest has to be stopped. I feel like everyone is pussyfooting around a load of bigots. They shouldn’t be allowed anywhere near the schools. These are people with a religious extremist agenda. They are holding schools under siege.”

Phillips said she would ask for an exclusion zone around the school to allow pupils to attend lessons without being disturbed by the protests.

Afsar denied the protests were promoting an extremist agenda. He said: “That’s absolute nonsense. That’s not what is happening. I am here for the community and they feel the school are being intolerant and I am supporting them.”

Hewitt-Clarkson said the school would pursue an injunction to stop the protesters from gathering outside, and claimed the protests were a “one-man show”.

She said: “The first time I met Shakeel he slammed his hand on my desk and demanded that we stop teaching anything about LGBT rights. He was very agitated. He describes himself as a general in army and uses words like battles, army, soldiers, and I have to keep reminding him that this is a primary school. We call it the Shakeel show.”

Headteacher Sarah Hewitt-Clarkson says the protests at her school are a ‘one-man show’. Photograph: David Sillitoe/The Guardian

At Parkfield community primary school in the predominantly Muslim Alum Rock area of Birmingham, where the first protests took place, there has been a moratorium. Nazir Afzal, the Crown Prosecution Service’s former lead on child sexual abuse, has been brought in as a mediator and both the school and parents have remained silent, seeking to distance themselves from other recent activity on the issue.

In other parts of the country groups have also been created. In Oldham in Greater Manchester, 500 parents have joined the Oldham Parents Forum and plan to lobby all 60 schools in the area to begin talks with parents over LGBT lessons.

Nasim Ashraf, a member of the religious group Oldham Interfaith Forum, said he started the forum. Ashraf and his wife, Hafisan Zaman, received payouts from a number of national newspapers when they were falsely accused of a Trojan horse plot to take over Clarksfield primary school in the area.

Ashraf acknowledges his own children are not affected by the LGBT teaching. One of his daughters is at university and his other child is at a Church of England school and will have left by the time the programme is rolled out into the curriculum.

However, he was allegedly called on by parents who were finding it difficult to articulate their concerns. His group has approached seven schools and have plans to speak to 60 in total.

He said: “Some of these parents can’t articulate what they feel and some of them don’t even know what Islam says about this issue. I am here to guide them. Our biggest asset is our children and we need to make sure the schools are adhering to guidelines and policies when teaching RSE [relationships and sex education] and taking into account parents’ beliefs.”

The Manchester Parents Group [see footnote] is headed by Shebby Gujjar Khan, a 30-year-old accountant who has no children. His group, which has almost 250 members, called for protests at primary schools across the region and for parents to withdraw their children. This resulted in parents at several schools, including William Hulme’s grammar school in Whalley Range and Acacias community primary school in Burnage, contacting the management about sex education lessons.

Khan, who says he created his group after parents raised concerns with him about a transgender child attending a local secondary school, claims groups have also been created in Blackpool, Preston, Bradford and Liverpool.

He said: “This is about morality. We have our own religious beliefs and they need to be respected.”

From September 2020, primary schools in England will be required to teach relationship lessons, including classes that will reflect the fact some children have same-sex parents. Parents will not have the right to withdraw pupils from these classes.

The education secretary, Damian Hinds, said the protests had been “hijacked by individuals with a vested interest and no links to the schools”.

He added: “It is unacceptable that children at Anderton Park are missing out on education because of the threat of protests. There is no place for protests outside school gates. They can frighten children, intimidate staff and parents. It is time for these protests to stop.”

Hewitt-Clarkson says she will not bow to the protesters. “This is not about LGBT. This is all about control, coercion, manipulation, dehumanisation of me because I will break and I will be crushed and they will be victorious. We’ve seen this play out here but I won’t meet them and I won’t meet their demands, and they are not winning and that’s why it has escalated. They have to be the victors at any cost, but they will not win.”

• Footnote added 6 June 2019: the Manchester Parents Group referenced in this article is unrelated to a voluntary organisation with the same name that supports families and friends of lesbian, gay, bisexual and transgender people. This group’s website is: manpg.co.uk.