VERBAL abuse and physical threats against teachers on social media are on the rise and must be stopped by schools taking a tough line with offenders, it has been warned.
Headteachers in the county said online abuse has become more common as the use of social networks has grown, with a potentially 'horrendous' impact on staff.
Unions warned abuse in Oxfordshire ranged from foul language and 'bullying' to physical threats.
It comes as a national survey of 1,500 teachers by teaching union NASUWT revealed 50 per cent had been abused online by parents or pupils.
NASUWT Oxfordshire federation secretary Michelle Codrington-Rogers said: "The main issue is that parents and students are using social media to abuse parents and staff.
"There are posts where parents say 'I have just had a run in with such and such at school, they're a real cow'.
"We are working with schools, with the county council to encourage a zero tolerance policy so that when these posts are brought to light the headteacher will come down on the parent like a ton of bricks."
Ms Codrington-Rogers said a number of schools had actually written to parents warning about posts on their Facebook pages. She added that older headteachers who may not have the same experience with social media as parents or pupils needed help to understand its intricacies.
National Union of Teachers Oxfordshire spokesman Gawain Little said: "In the cases I have dealt with I am aware of people who have been abusive and doing someone down as a professional with foul language and that sort of thing.
"I am aware of situations where it has been physical threats as well.
"The problem is that on social media what can start out as a discussion about what is going on in a school can build into quite personal comments about teachers.
"These are comments that would not be acceptable in the workplace.
"It reminds me of signs you see on trains and in post offices saying 'abuse of our staff will not be tolerated'.
"That should be our approach as well."
Windmill Primary School headteacher Lynn Knapp said her school in Headington dealt with its first incident of online abuse just a few weeks ago.
She said: "A parent was not happy with a decision a teacher had taken and he wrote something on his private Facebook which was quite obscene about that teacher.
"Because it was a private page we decided the teacher would deal with it himself, he went to the parent and asked him to take it down.
"We have a specific policy for our own school Facebook page but we have never had a problem with that.
"It is very hard to stop it happening. People forget that when it is on Facebook it still has an impact on how people feel."
Mrs Knapp said that schools had to accept there would always be a risk associated with social media but could act quickly to sort issues out before they got out of hand.
Oxford Spires Academy headteacher Sue Croft said they had a policy on social media but also dealt with issues on a case by case basis. She said there were typically one or two instances of abuse on social media in an academic year.
She said it tended to involve a parent 'having a rant' on social media and that most of the time it was easily resolved.
She added: "When a parent does have a bit of a rant on social media it is usually because they are desperately worried about something.
"Usually good communication can help them solve whatever issues they are worried about.
"But sometimes we do have to say enough is enough, we are not going to have abuse.
"The problem with social media is that people can get worked up in isolation and it is easy to write about it when you are not face to face with somebody.
"It is horrendous when it happens, particularly for young teaches or for anyone feeling they are doing a really hard job."