The scrapping of key stage 3 Sats has meant a significant increase in teachers' workload as schools continue to test children, new research has found.
Headteachers now ask teachers to mark exams and complete a detailed examination of their own performance, according to the study by teaching union the NASUWT, due to be unveiled at its conference this weekend.
Almost 70 per cent of the 2,000 teachers surveyed say they now spend more time on assessment for 14-year-olds, nearly two years after the national tests were scrapped in the wake of the 2008 marking fiasco.
The union says the Government must now urgently review KS3 assessment because of the "adverse workload implications". The implications of the survey's findings will be debated at this weekend's conference.
NASUWT bosses say problems at KS3 show that retaining external testing in primary schools is a "necessity", that the tests "protect" teachers and heads from "excessive workload burdens" and prevent them being distracted from their "core responsibilities".
About 63 per cent of respondents say their increased workload is caused by having to assess children's performance in more detail; 57 per cent because of increased moderating and checking; and 28 per cent because of the increased burden of collating work. Some 20 per cent say their school has introduced more detailed reporting arrangements.
The study shows that 17 per cent of teachers' workload has risen by 10 hours for each of their Year 9 groups, 43 per cent by at least five hours, and 87 per cent by at least one hour.
About half of all teachers surveyed say mock tests are still used in their school and that they have to mark two sets of exams. A total of 77 per cent say teacher assessment has replaced the Sats, while 26 per cent say new tests had been introduced in place of the national tests.
The union's general secretary Chris Keates said: "The NASUWT has warned consistently that the obsessive opponents of the tests are careering down a path which will increase workload for teachers.
"This survey vindicates the NASUWT's position.
"Since KS3 Sats were abolished, secondary teachers in many schools now have even more workload. They face excessively burdensome assessment and not only are they having to administer the tests, but also mark them themselves.
"It is reckless to abandon Sats without considering what will replace them. Those who are now calling for the removal of KS2 Sats should take heed. They are doing teachers and pupils no favours."
Ian McNeilly, director of the National Association for the Teaching of English, said: "There was little point in getting rid of the Sats if they are going to be replaced with more tests marked by the teacher."
Peter Kent, head of Lawrence Sheriff School in Rugby, Warwickshire, said ending the Sats had made lessons more interesting and taken pressure off pupils and staff.
Staff teach KS3 over two years rather than three.
"In our school, workload has significantly reduced because we don't have these target-driven exams in the way during our programme," he said. "Subjects take their own route, some choose to begin GCSE study straight away, some spend more time doing in-depth projects, but it has made us more creative."