Teachers cannot always prevent the “horrific” abuse of children and should not be “criminalised” if they are unable to do so, a conference has heard.

Speaking at the ATL teaching union’s annual conference in Liverpool, teacher and union member Niamh Sweeney said she could not “excuse or explain” the “horrific stories” of children such as Victoria Climbié, Jessica Chapman and Daniel Pelka.

She said: “I cannot tell you why some people abuse, manipulate, exploit and kill children. Although I would like to prevent it from ever happening again I know that unfortunately it will and that I can’t.”

Ms Sweeney said that prime minister David Cameron’s threat to criminalise teachers for failing to report concerns about child sexual exploitation would actually increase risks to children.  

“If [David] Cameron goes ahead with his knee-jerk response to these awful crimes, which is to effectively criminalise teachers, it will leave children and young people more vulnerable, not less,” she said.

Ms Sweeney’s comments come after prime minister David Cameron announced this month that teachers who failed to report concerns about child sexual exploitation could face up to five years in prison. 

Ms Sweeney said the rise in referrals to children’s social services in the wake of the Baby P case had left the services “near breaking point”.

“In far too many schools the role of safeguarding is falling on a distinct approachable few,” she said, adding that these teachers were “overburdened”, “out of their depth” and “burned out”.

During the same debate, Helen Porter, an ATL member based in Berkshire, said the government’s measures “could not make us want to protect [children] more than we already do”.

However, she warned: “The threat of criminalisation might frighten and confuse [teachers], especially if we haven’t been adequately trained.”

She added that the move would “further deepen the teacher recruitment crisis”.

Teachers also used the conference to raise concerns about the government’s demand for schools to promote “British values”.

Robin Bevan, head of Southend High School for Boys, said the demand was an act of “political posturing”.

He urged teachers to distance themselves from the order, saying: “When it comes to the new requirement of promoting fundamental British values, including the role of law, here is one law that I would actively encourage you to disengage from.”

Under the reforms, introduced in the wake of the Trojan Horse scandal last year, Ofsted must assess whether schools promote “fundamental British values”.

However, Mr Bevan said: “”If these fundamental British values change with time, then they are hardly fundamental. And let’s face it, they have changed with time. We now allow women to vote. We no longer chemically castrate homosexuals.”

Mr Bevan later said: “Even more extraordinary is the notion that Ofsted will somehow be the agent of micro-fascism in assessing the extent to which schools actively promote these fundamental British values.”

Calling on delegates to back a resolution asking ATL’s executive to monitor how British values are being policed, Mr Bevan said: “There is the well-publicised issue of the radicalisation of a very small number of students.

“But the solution being proposed is totally out of proportion. It’s the wrong approach, at the wrong scale, with the wrong model of learning and the wrong method of assessing its effectiveness.”