Most accusations against teachers in Wales are dropped
Over half of accusations made against teachers and teaching assistants by pupils in Wales turned out to be false, malicious or unfounded.
Figures for the last five years obtained by BBC Wales found 55% of 312 allegations were later dropped.
Teaching unions say that to try to deal with the problem, more action should be taken against those who make false or malicious claims.
The Welsh government said it is updating its guidance on the issue.
It said it will include advice on what consideration governing bodies should give to taking action against accusers.
But it added that it was important to take children's claims seriously and not deter pupils with genuine complaints from coming forward.
The Children's Commissioner for Wales Keith Towler said he wanted the Welsh government to publish their new guidance "as a matter of urgency".
The figures, obtained by BBC Wales under the Freedom of Information Act, show that between 2006 and 2011, 312 allegations were made against teachers and teaching assistants at Welsh schools.
But 174 of those, or 55.7%, were later found to be either false, unfounded or malicious.
A total of 103 cases were investigated by police and two teachers or assistants were convicted of a crime.
Of those facing accusations, 121 were suspended while the allegations were investigated.
The NUT and NASUWT both say the problem could be even bigger than the figures suggest.
Three councils - Swansea, Ceredigion and Caerphilly - were not able to provide figures on the issue and some were only able to provide statistics for the past few years.
Unions insisted more needs to be done to protect teachers from false accusations, while balancing the right of pupils to make genuine complaints.
They also suggested the complaints procedure should be reviewed so that teachers can be treated more fairly. They say they are often treated as guilty until they can prove themselves innocent.
"This is a matter of extreme concern for us and I know it's something that teachers are worried about," said Rex Phillips, Wales organiser for the NASUWT.
"It's every teacher's worst nightmare to have a false allegation made against them. Their reputation is damaged and they often find it hard to go back to work, even though they've been completely exonerated.
"We just want teachers to be treated fairly. Once an allegation is made, a teacher is often suspended immediately without even a bit of consideration given to if it can be true or not.
"There's no 'innocent until proven guilty'."
He said he would like to see police using their powers more to deal with pupils who have been proven to have made a false or malicious allegation.
"We would like a system where pupils can't make false allegations with impunity," he said.
"The police can issue a caution to the individual but I'm only aware of one case where this happened. I think it would send out a message to others that this will not be tolerated."
David Evans, Wales secretary of the NUT, said: "You have to realise that once an allegation is made, the rumour mill starts in schools and even if a teacher is later exonerated, there's the 'no smoke without fire' situation.
"Something needs to be done about it. There should be a complete overhaul of procedures and more should be done against those making false allegations."
Newport Council, where 71% of allegations were unfounded, said it followed guidelines when dealing with claims.
"Newport City Council and our schools take allegations against teachers and teaching assistants seriously and ensure swift action is taken in the interests of all parties concerned," a spokesperson said.
Children's Commissioner for Wales Keith Towler said: "Classrooms should be safe places for both teachers and pupils.
"What we need to be doing is fostering a culture of respect between teachers and their pupils instead of pitching them against each other.
"I am particularly concerned by the statement about the proposed criminalisation of children found to have made false accusations - this could act as a considerable disincentive for those children who do have an allegation to make.
"We have waited for new guidance from the Welsh government for quite some time and I press them to publish as a matter of urgency."
The Welsh government said it did not want to see teachers being falsely accused, but added: "We must not do anything that might undermine the child's right to be heard or deter children with genuine complaints from coming forward.
"There is provision within the Education Act 2011 that provides anonymity to teachers facing accusations of criminal behaviour against pupils at school.
"The provision, which applies to both England and Wales, is not applicable to the General Teaching Council for Wales investigations, hearings or outcomes.
"We have a range of policies in place that set out clearly how allegations against a teacher should be handled within the school, and a process for independent external investigation where this is required.
"The Welsh government is currently working with stakeholders, including teaching unions, to update its guidance on handling of staff disciplinary cases.
"In the guidance, which sets out a fair and transparent process for the handling of disciplinary cases against teachers, we intend to make provision relating to the handling of malicious or false accusations and what consideration governing bodies should give to taking action against accusers."