By Justin Parkinson
BBC News education reporter at the ATL conference
Government plans to give England's secondary schools more independence are a "mess", a union leader has saidy.
Mary Bousted: Gave a warning of "ghetto" schools
The Education and Inspections Bill proposes head teachers be given more say over admissions and budgets, and parents a greater choice of schools.
But Mary Bousted, general secretary of the Association of Teachers and Lecturers, said the plans risked creating "schools for the underclass".
She was addressing the ATL's annual conference in Gateshead.
The ATL starts the teachers' union conference season.
The education bill, currently going through Parliament, calls for parents to be given a greater choice of schools for their children and for businesses, charities and faith groups to have a greater role in their running.
In her speech in Gateshead on Monday, Ms Bousted said: "Why has this government made such a mess of its education bill?
"Why does it believe that standards will rise if schools are run by businesses?
"Let us remind ministers that many parents cannot exercise a choice in the school they send their child to - either they live in rural areas where one school serves the whole community, or they live in the wrong area and cannot get access to their school of choice."
She added: "Popular schools will never be able to expand to meet unlimited demand.
"And whilst money follows pupils, those schools serving the most disadvantaged communities will lose resources.
"The danger is that those who need the best education to increase their life chances will be left at the margins, in schools with unbalanced intakes, inadequate resources and poor attainment."
Working-class children would be "ghettoised into schools for the underclass where peer group pressure is not to achieve but to reject education and all that it can offer", Ms Bousted warned.
She advocated schools with a socially mixed intake.
A spokesman for the Department for Education and Skills said: "These accusations are simply untrue.
"The proposals in the education bill will raise standards across the education system, specifically tackling educational disadvantage."
And he said proposals on better discipline, more individual and small group teaching, stronger leadership and tapping into the energy of partners in the community, were focused on raising standards.
They would strengthen every school but particularly those in deprived communities.
Ms Bousted's speech opens the ATL conference, which lasts until Wednesday.
Delegates will discuss issues including racism in the classroom and the effects of media coverage of terrorism on children.
The union will also consider a call for a return to compulsory languages for 14 to 16-year-olds in England.
Conferences organised by the NASUWT and the National Union of Teachers also take place over the Easter period.