text: "Parents no longer have the certainty when they send their child to school that they will be taught by qualified teachers," says NASUWT leader Chris Keates.
  Labour's Tristram Hunt says "this is nothing less than a scandal".
  But the Conservatives say there are fewer teachers in school without qualified status than in 2010.
  The NASUWT teachers' union, holding its annual conference in Cardiff, will hear claims that more teachers without qualified teacher status are being used in schools.
  The union has asked its members about their experiences. Among the 4,600 who responded 61% said they were "working alongside unqualified staff",  with 66% claiming the situation was "deteriorating" because of funding problems.
  "This is jeopardising the educational progress of children," said Ms Keates who attacked the use of unqualified staff as a "crude cost-cutting measure".
  Teachers responding to the union's survey included comments such as: "They lack any training in classroom management and discipline" and "I feel that parents are being misled by the quality of teaching within the school."
  The use of unqualified teachers has become a general election issue.
  Labour has campaigned against allowing academies and free schools to employ teachers who do not have qualified teacher status or who are training towards being qualified.
  "The rising number of unqualified teachers in our schools shows yet again that the Tory plan is threatening standards and failing children and working families," said shadow education secretary Tristram Hunt.
  "David Cameron has removed the requirement for teachers to be qualified, and as a result over 400,000 children are now being taught by unqualified teachers without receiving training in skills vital to the profession such as classroom discipline, safeguarding and how to deliver effective teaching for all children."
  The Liberal Democrats also want to require teachers to have qualified status.
  But both Liberal Democrats and the Conservatives say there were more unqualified teachers in schools when Labour were in power. They reject the suggestion that the use of unqualified teachers is increasing.
  A Conservative party spokesman said: "The number of teachers without qualified status has gone down since 2010. And we need to keep this in perspective - only 3.7% of teachers are 'unqualified'.
  "But most importantly, we've given head teachers more freedom over the teachers they employ because we trust them to know what is best for their schools.
  "There are some brilliant teachers who have not got qualified teacher status - nuns, great linguists, computer scientists, engineers and other specialists that inspire their pupils. They may have worked in the independent sector or have experience in the outside world."
  A spokesman for the Liberal Democrats said they would "change the law to guarantee a qualified teacher in every classroom".
  "Teaching must be recognised as the vitally important and high status profession that it is, able to attract and retain the very best people."
  "It is good news that there are now fewer unqualified teachers working in schools than under the previous Labour government.  However, every child deserves to be taught by a qualified teacher, regardless of what type of school they attend."
  The most recent Department for Education figures available, for 2013, show the number of unqualified teachers rose compared with the previous year, from 14,800 to 17,100, but is lower than in 2010, when there were 17,800 of teachers without qualified teacher status.
  However for academies, the proportion of unqualified teachers has risen each year since 2010, from 2,200 to 7,900.
target: A teachers' union is warning that schools are increasingly likely to use unqualified teaching staff.