Teaching union the NUT has called for this year’s SATs to be suspended after claiming the government’s new system for primary assessment has “come apart at the seams”.

The classroom union made its plea this evening following criticism of the education secretary’s system for testing and assessment of KS1 and KS2 pupils.

In a statement on its website, the NUT argued that the government requirements in relation to teacher assessments of children’s writing standards, published this month, have “come far too late in the process”.

The union believes the detail in the exemplifications of the required standards, and the number of separate pieces of evidence required for each individual assessment, has made it “impossible for teachers to deliver in the few months between February and June”.

The NUT said: “These proposals add to a chaotic heap of other demands. The reporting date for teachers’ assessments has been brought forward. The ‘expected standard’ that children are required to meet has been pushed upwards, beyond the reach of far too many pupils. The consequences of this shift on the requirement on schools to meet floor standards have not been thought through.

“Ministers have failed the test of competence. [Education secretary] Nicky Morgan’s pledge to give a year’s notice of substantial changes has been revealed as just a hollow promise.”

In an article on the TES website today, Mary Bousted, general secretary of the ATL classroom union, has criticised the government’s new system.

She said: “Many teachers, who had been waiting anxiously for these materials, must, when they opened them, have despaired. Not only has the standard for reaching the expected level been very significantly raised (more akin to an old level 5 rather than the promised 4b), but also the assessment burden placed on Year 6 teachers is huge and unworkable

All the teaching unions are expected to meet on Thursday to discuss a joint response.

A DfE spokesperson said: “It is disappointing to see that the NUT and ATL are taking this approach, which would disrupt children’s education, rather than working with us constructively as other unions have.”

“The assessment framework for Key Stage 2 was published in September 2015 - the beginning of the academic year in which these assessments are due to be made. We have been clear that the exemplification materials published recently are intended to be a guide against which to assess a pupil’s standard.”