An anonymous group of pupil activists has disrupted the latest round of national testing.
The group placed the maths national test on the internet on Monday - a day before pupils were scheduled to take the exam.
In an email to Norwegian news bureau NTB, the activists claimed they are angry with the Government for pressing ahead with this year's round of national testing, despite widespread strike action taken by pupils last month. Like many Norwegian pupils, they are opposed to ranking schools in published league tables.
The group is demanding that teachers be paid for marking the tests. They also want the exam's content to reflect the demands of the Norwegian curriculum, rather than the wishes of the Organisation for Economic Co-operation and Development, which compiles international comparative studies of student performance.
In a veiled attack on schools and teachers, the education minister Kristin Clement said that the latest incident was "nothing but sabotage and the result of disloyalty".
Schools and teachers are instructed not to make the contents of the test known to pupils prior to the exam, although they receive the test several days beforehand.
The minister said the results will stand even though 10,000 of the 60,000 15 to 16-year-olds who took the exam are thought to have downloaded it from the internet beforehand.
The education ministry, however, plans to review the procedure for exam papers distribution.
National tests in core subjects for pupils aged nine-17 were introduced last year.