Teachers have moved one step closer to a boycott of primary school tests after voting to carry out a ballot over fears classrooms are becoming “exam factories”.

Delegates at the National Union of Teachers (NUT) conference backed proposals for schools in England to refuse to take part in the tests for seven- and 11-year-olds this May.

Teachers are battling the Government over the use of “baseline” tests being introduced in the first year of a child’s formal eduction, as well as reformed spelling, punctuation and grammar tests for older children, which have been made more demanding.

If Nicky Morgan, the Education Secretary, does not back down then the union will consider a ballot to boycott all primary school tests in 2017.

“Teachers are angry and dismayed at the primary tests, which they believe are age inappropriate. Teachers are wasting precious time on preparing children for tests at the expense of offering a vibrant engaging education for their pupils,” said Christine Blower, general-secretary of the NUT.

“Far from improving outcomes for 11 year olds, the endless high-stakes testing of such young children could easily switch children off from learning, increase their anxiety levels, and harm their self-confidence – a vital ingredient for successful learning.”​

After the vote, which took place at the NUT’s annual conference in Brighton yesterday, a spokesman for the Department of Education said the planned action would “disrupt” children’s education.

The NUT is not one of the trade unions affiliated to the Labour Party.