At least two UK schools have banned the controversial app Yik Yak after it was used by pupils as a platform for cyberbullying.

The App has already been banned in 130,000 schools in the US, with pupils using the anonymous online public messaging board service to spread vicous rumours and insults about their targets.

Designed in the US, the free app allows users to post messages visible to anyone within 1.5 miles without the need for a profile or a user name.

Designed as a means of posting news and messages in local communities and on college campuses, the app has prompted experts to warn of its dangers as a tool for cyberbullies.

Writing for Fox News, psychiatrist Dr Keith Ablow described Yik Yak as "the most dangerous form of social media I've ever seen.

"Psychologically, Yik Yak actually removes all pretence of being a person with empathy, genuinely connected to other human beings," he wrote.

At Highams Park School in east London, the headteacher, Steve Riches, has told pupils not to download the app and to delete if if it is already on their mobile devices. He has contacted the creators to ask them to block the device from working within school perimeters.

He wrote to parents recently "Some of the posts we have already seen are indeed offensive, harassing, hate orientated, harmful, defamatory, probably illegal and are targeted at named individuals."

He added: "This can lead to severe cases of bullying and creates tensions throughout the school community."

Riches advised pupils that anyone found posting harmful material with the app could face police action.

At nearby Chingford Foundation School, the app has been blocked from the school's wi-fi network and pupils warned of the risks of using it.

Pupil Chloe Reid, 18, said she had started a petition asking the creators to withdraw the app.

"Students at the school I attend are using Yik Yak to post obscene comments and reveal personal details about their peers," she told the Times.

The app can be used by anyone over 17, and hostile messages are removed if they are "downvoted" enough by fellow users, but critics say the age limit is not enforced.

"I don't think parents or teachers know enough about the social media platforms and apps that their children use," said Reid.

Co-founder of Yik Yak, Brooks Buffington said that the company had blocked access to the app at 85% of US schools, and British schools could request the same.

'We definitely did not make the app for this - we are doing everything in our power to stop that happening,' creator Tyler Droll told MailOnline.