Pupils using technology and social media to subject teachers to cyber-bullying is a problem which must be confronted head on, a union leader has said.

Margaret Smith, president of the Scottish Secondary Teachers' Association, said there are "truly shocking examples" of this.

False Facebook pages have been created in the name of some teachers and filled with "scurrilous content including explicit sexual imagery", she claimed.

Pictures of staff have been taken without their consent and posted on YouTube, she claimed.

Ms Smith will raise her concerns during a speech today at the union's annual congress in Peebles.

She said: "A new dimension to the seemingly eternal problem of indiscipline has arisen. We are only too aware of problems involving the abuse of social media networks, mobile phones etc, among pupils but far too little attention has been given to the cyber bullying of teachers.

"Make no mistake, there have been truly shocking examples of abuse of teaching staff by pupils: photographs taken without consent and posted on You Tube; false Facebook pages created, filled with scurrilous content including explicit sexual imagery; and the use of technology generally as yet another resource to abuse and undermine teachers.

"I am convinced that the cases we hear about are the tip of the iceberg and that cyber bullying of teachers is an issue that the SSTA (Scottish Secondary Teachers' Association) must confront head-on."

Ms Smith also raised the "old hobby horse: pupil indiscipline" as she argued that a more consistent approach is needed to tackle bad behaviour in the classroom.

While fewer pupils are being excluded from schools, the "statistics can be misleading".

There is an "inconsistent approach often taken because of the political determination to reduce exclusion figures".

This is not a problem solely for disadvantaged areas, she said.

"Schools within the same catchment area can have vastly different standards as to what behaviour is tolerated, even condoned.

"What is needed is a consistent approach to dealing with indiscipline, an acceptance that some behaviour - violence, threats, verbal abuse of teachers - cannot be tolerated and a national consensus for dealing with such behaviour arrived at."