Pupils with behaviour problems have been taught in makeshift offices in a "postcode lottery" of special needs provision, teachers claim.
The conference complained about special schools being closed
Scores of pupils with emotional and behavioural problems remain undiagnosed in mainstream classrooms, the NASUWT teaching union annual conference heard.
It heard a call for miniumum national standards of entitlement in England.
But the government said parents now had more choice, with specialist provision within mainstream schools.
South East Essex delegate Dan McCarthy told the conference, in Belfast: "This is making me very angry and frustrated.
"It's not just the closure of special schools that is doing this. It's also what's happening in our mainstream school and in our classes.
"Within these classes are large numbers of pupils who are undiagnosed.
"I had a pupil who ran around a tree in a playground. When anybody shouted at him he wet himself."
Another had climbed out of a tower block window and shouted, "I am a cabbage".
Nobody wanted to deal with these pupils' mental health problems, Mr McCarthy said.
The inclusion co-ordinator at Bodmin College in Cornwall, Kathy Wallis, told the conference many pupils were being taught in unsuitable makeshift locations, because of inclusion policies.
She said: "Would you like your child to be taught in the back room of the Citizens Advice Bureau?
"How would you like to be taught in a room at the bank with no resources? It makes practical science lessons very challenging."
She said children who were school phobics, who had emotional and behavioural difficulties, who were on Asbos or pregnant were being taught together in this way in Cornwall.
"If you have somebody who is a school phobic in the same group as someone who has severe behaviour difficulties you are not going to address either of their needs," she added.
In a statement, Cornwall County Council said it was working to upgrade the accommodation for its six pupil referral units.
The North Cornwall one had moved last month from its former premises above a Barclays Bank branch to a new building.
"None of the PRUs are based in Citizens Advice Bureaux , however very occasionally a room at the Citizens Advice Bureau in Bodmin is used to meet with children who are medically unfit to travel to the North Cornwall PRU," the statement added.
Another conference delegate, Brian Cookson, said mainstream schools were "struggling valiantly" to cope following the closure of special schools, adding that provision for many students with special educational needs (SEN) "has been decimated".
"There should be in place a national minimum framework setting out minimum standards for SEN to ensure that pupils get the help and support they are entitled to.
"The postcode lottery of special educational needs provision must end."
Teachers were urged to go back to their local authorities and ensure pupils' educational needs were met.
The conference backed a motion calling for an end to the postcode lottery of special needs provision, but stopped short of urging the reinstatement of special schools and an end to their closure.
A spokesman for the Department for Education and Skills said SEN was a government priority.
"Parents now have greater choice - more than 20,000 children with complex special educational needs are now taught in specialist provision based in mainstream schools," he said.
Spending had risen and staff training had been improved.
Oftsed had reported that mainstream schools with special provision were "particularly successful in achieving high outcomes for pupils academically, socially and personally".