THOUSANDS of children will have their schooling ruined by the introduction of new tests later this year, education groups claimed yesterday. Primary school pupils will be under intense pressure as they sit the exams, according to the Education Action Group, which fears the tests would allow a return to the discredited system of secondary school entrance selection. But the Education Department has insisted that the new Secure Hongkong Attainment Tests, in Chinese, English and mathematics, were intended solely to help parents choose the most appropriate school for their child. It said there would be no resumption of the Secondary School Entrance Examination, which was abolished in 1978 and which dictated where a pupil went. Opponents of the tests believe they will cause stress to the tens of thousands of children in Primary Six who will have to sit the exams in December each year. The president of the Association of Lecturers at Colleges of Education, Mr Gregory Lam Shu-wing, said schooling would suffer because subjects not included in the territory-wide tests would be ignored in the quest for the best results in English, Chinese and mathematics. The education of 11-year-olds would be jeopardised if other academic subjects and general development classes had to be sidelined, he said. ''We feel these tests will have bad implications for primary education,'' Mr Lam said. ''The curriculum will become examination-driven and primary pupils will not gain an all-round development. ''We are also apprehensive that the tests will revive the old system of secondary school entrance exams and we don't want pupils to go through the same painful experience that we had. ''If the Education Department believes parents need to know the relative standard of their children, they can refer to the attainment tests which have long been in use.'' But a senior education officer in the Education Department's research section, Mr Anthony Poon Hon-hung, denounced the criticism as misrepresenting the situation. ''These tests have nothing to do with the allocation of places,'' he said. ''That depends on how the children perform in the internal school tests for the Secondary School Places Allocation system, and on what their parents choose. That procedure will continue. ''The tests provide information for parents to allow them to make an informed choice about what type of school would be best for their child, given his or her language capability.'' Mr Poon denied that primary school teachers would be encouraged to concentrate on the test subjects of Chinese, English and mathematics.