British police are looking into cases of sexual assault reported by girls amid a deluge of witness testimonies collated online that is embroiling some of the country's top private schools.

Nearly 6,000 incidents have been described anonymously on the website "Everyone's Invited". Its founder Soma Sara said they exposed a "rape culture" in schools and beyond.

The harrowing accounts by schoolgirls come after a London police officer was remanded in custody on March 16, charged with the kidnap and murder of a woman who vanished as she walked home.

The disappearance of Sarah Everard sparked outrage and a national debate on women's safety, and raised pressure on London's Metropolitan Police force after officers broke up a vigil for Everard, forcibly dragging away some female protesters.

The Met said officers were determining whether any potential victims at schools could be encouraged to report crimes, and "a number of reports of specific offences" were being examined.

Incidents involving boys from more than 100 schools have been collated, including some attending elite fee-paying ones such as Sherborne, Westminster and Eton -- where Prime Minister Boris Johnson and Prince William studied.

Pupils demanding change at the private Highgate School in London walked out of classes this week after a dossier with more than 200 testimonies by former and current students was published online. The school said it was launching an independent review.

"I think it's more widespread than private schools," Detective Superintendent Mel Laremore, the Met's lead officer for rape and sexual offences, stressed on BBC radio Saturday.

"I think we're still looking into the exact scope of how wide this is spread. But certainly I know there's already over 100 schools cited on the website, which do reach out to national parameters," she said.

However, private schools are not obliged to adhere to the government's "safer schools" guidance followed by state schools, Laremore noted.

University student Sara, who started sharing witness testimonies in June 2020 after suffering an assault herself, said the focus should go beyond a handful of elite schools.

"When we narrow our focus on a school, a demographic, or as an individual, we risk making these cases seem like anomalies. But this isn't rare, it happens all the time," she wrote in Friday's i newspaper.

"When we direct the blame onto a person or place we are undermining the most important message: rape culture is everywhere. And because it's everywhere it affects everyone."