Tens of thousands of primary school children were set to miss their Sats today in a boycott being staged across the country.

Some schools have already confirmed they would not be holding the tests and more, which have not informed their council of their intentions, were expected to take part in the boycott. It is understood many pupils in Shropshire and Telford & Wrekin would take the tests but the results would not be sent for analysis.

Christine Hargest, National Union of Teachers divisional secretary for Shropshire, said: “What we are trying to do is stop league tables.”

The results from the tests are used to compile tables, which Mrs Hargest said were “divisive”.

A spokeswoman for Shropshire Council said it believed there would only be a limited impact on its primary schools with between 10 and 15 per cent affected.

What action is taken is being left by the NUT and the other union involved, the NAHT, to individual heads or deputies.

In Telford & Wrekin it is understood that up to 50 per of schools might be affected.

A council spokesman said: “Those schools that have decided to boycott the tests will be operating alternative assessment procedures in order to ensure that all children are given a National Curriculum level of attainment.

“This assessment grade can then be passed on to each child’s secondary school.”

Christine Blower, general secretary of the NUT said that there were “categorically” enough schools taking action to scupper primary school league tables.

Support ranged from 30 per cent of schools in some areas to more than 70 per cent in others, she said.

About 600,000 pupils aged 10 and 11 are due to take Sats this week, starting with reading tests today, followed by writing and spelling papers and then maths on Wednesday and Thursday.

The results are usually used to create league tables – but these will be thrown into disarray by the boycott.

Ofsted inspections are also likely to be affected as Sats results are a key measure used by the inspectorate when forming judgments on schools.

The unions say the tests are bad for children, teachers and education, cause unnecessary stress and lead to the creation of league tables which undermine the work of schools and heads.

By Education Correspondent Dave Morris