Glasgow could be the first flashpoint in a renewed clash over standardised tests, now widely regarded by authorities as providing useful complementary evidence of children’s progress and a base for value-added measures.

Many believe them to be more reliable and valid than confirmatory national tests, and some, such as East Renfrewshire, Stirling and Aberdeen, have introduced them without overt opposition.

In Glasgow, however, the local association has demanded full union backing for a campaign against tests in a cluster of schools . Mr Hart said teachers were “outraged ” at the council ‘s “back to the dark ages ” move and wants permission from union headquarters to withdraw co-operation .

Nationally, the union has already warned it will oppose compulsory external testing, as it did when a coalition of teachers and parents successfully resisted the plans of Michael Forsyth, Tory education minister, in the early 1990s.

Current ministers are under pressure from some authorities to support the introduction of externally set and marked tests following the national consultation on 5 - 14 assessment. But Mr Hart cautioned: “If Scotland goes down this road, we might just as well have Blunkett .”

This was a reference to te standardised national testing imposed by the Education Secretary south of the border at key stages in primaries and the early years of secondary . Mr Hart said Glasgow’s decision to proceed with piloting came out of the blue, only days before the two-week Easter break. The tests are due to be conducted in the St Mungo ‘s Academy and Bannerman High clusters during the first two weeks of May. All pupils from primary 2 up to secondary 2 will be tested in writing and math s, using materials produced by Nelson Publishing and the National Foundation for Educational Research (NFER). The tests are widely used south of the border and increasingly in other Scottish authorities.

Mr Hart said the union had previously been assured that matters relating to testing would be first raised at the quality and standards sub committee . Teachers in the cluster schools were “astonished ” when told tests were to be conducted immediately after they returned from holiday .

Mr Hart said they were “deeply disturbed” at the prospect of pupils being tested on the basis of their age. “These tests cut across national testing and make a mockery of differentiation. Many children will not be able to cope with them. Tests on this model may result in some children being totally demoralised when they are asked to attempt tests which are clearly not appropriate to their level of skill and development .” Other union sources fear test results will hit schools in certain parts of the city and set up some as failures .