MP Jess Phillips has accused the government of “failing young people” following an outpouring of complaints of sexual abuse in schools.

Labour has called for “swift and decisive action” after more than 9,000 reports were posted on the Everyone’s Invited website, where survivors can anonymously share their experiences of misogyny, harassment, abuse and assault.

Phillips said: “The reason that people don’t report to the police is because I’m afraid to say under this government we have seen a massive and dwindling amount of charges and convictions.

“People don’t believe that they’re going to be believed and also you know how traumatising it would be? Imagine you’re a 13-year-old girl, you’ve just been raped in the toilets of your school and you go and you tell a teacher and nothing is done by the school, and then you’re expected to go back into the classroom and sit next to that pupil.

“Now I have handled numerous cases like that, the only thing the government has done about this in the past four years, when they’ve known full well what’s going on, the only thing they’ve done was to put in place new guidance for teachers which they have not tried to make sure that teachers know about.

“And the only reason they did that was because a kid who was raped took the then-education secretary to court. That’s the lengths that people have to go to to be believed.”

Meanwhile the Conservative MP who oversaw a report into the issue in 2016 said schools regulator Ofsted should conduct a “deep dive” to establish what was happening.

Maria Miller, former chairwoman of the Commons Women and Equalities Committee, said it appeared nothing had changed in the five years since it published its findings.

Education secretary Gavin Williamson described the allegations which have emerged in recent days as “shocking and abhorrent”.

Soma Sara, who founded Everyone’s Invited, has said a “rape culture” is “endemic” within the education system.

In a letter to Williamson, shadow education secretary Kate Green and shadow domestic violence and safeguarding minister Jess Phillips called on the government to develop a national strategy to tackle the issue.

“Swift and decisive action is needed to make sure that the education system is safe for every young person, and that sexist or misogynistic attitudes towards women and girls are stamped out early,” they said.

Green said: “It is extremely concerning to see these reports of sexual harassment and abuse across the education system.

“Ministers have let young people down with their dangerous and irresponsible resistance to calls for a strategy to tackle sexism and sexual harassment in the education system.”

Miller told The Guardian that while the government had accepted many of her committee’s recommendations, schools appeared to be failing to implement new guidelines which had followed its report.

“In particular, the government changed the statutory guidance on how to tackle behaviour in schools to make it plain that peer-on-peer abuse was not acceptable and could never be justified as part of growing up,” she said.

“Following the inquiry, Ofsted was required to monitor how sexual harassment was recorded and what action was taken. What I think now, very strongly, is we need to have Ofsted do a deep dive on the issue of the handling of sexual harassment in schools.”

Earlier Williamson urged the victims of such “sickening acts” to raise concerns with someone they trust – such as a family member, friend, teacher or the police.

“No school – whether an independent school or state school – should ever be an environment where young people feel unsafe, let alone somewhere that sexual abuse can take place,” he tweeted.

“The allegations that I have heard in recent days are shocking and abhorrent.”

In a statement a government spokeswoman said ministers were “very concerned” at the number of allegations posted on the Everyone’s Invited website.

“The abuse of children and young people in all its forms is abhorrent,” the spokeswoman said.

“The vast majority of schools, colleges and universities take their safeguarding responsibilities very seriously, so it is particularly shocking when allegations of abuse are made in connection with a place of education where everyone should feel secure and be protected.

“Working together, the Department for Education, the Home Office and the National Police Chiefs’ Council are in contact with Everyone’s Invited to provide support, protection and advice to those who are reporting abuse, including on contacting professionals or the police if they wish.”