The Chairman of the state chapter of the union, Mr Samson Idowu, made the call in an interview with the News Agency of Nigeria (NAN) in Lagos.
Idowu said that the increasing number of unregistered schools was worrisome, noting that their activities were reducing education standards.
He advised the government to set up a taskforce that would comprise NUT members, officials of the state Ministry of Education and representatives of private school operators, for the closure.
He regretted that some private schools in the state operated in two-bedroom flats and uncompleted buildings.
“We are worried about the way people set up schools without approval; the schools do not have adequate classrooms.
“They are everywhere in Lagos; they even call some international or model schools; many of them do not have uniforms for pupils.
“This is ridiculous, and we will not tolerate it.
“It is not our duty to shut schools which do not have approval, but we can collaborate with the Ministry of Education to stop overzealous private school owners,’’ he said.
Idowu advised that pupils and students of such schools should be absorbed in registered ones.
“It is an act of indiscipline for people to enrich their pockets without following due process; this is what education has turned into in the country,’’ he said.
NAN reports that many unregistered private primary schools in the state charge low school fees.
This attracts low income earners’ patronage.
The Lagos State Government had in April allowed primary six pupils in both registered and unregistered schools to sit for a test for placement into JSS1 in public schools.
The state Commissioner for Education, Mrs Olayinka Oladunjoye, said that the government allowed pupils from unapproved schools to sit for the test to avoid denying them access to education.
She, however, said that the government would not tolerate the activities of unregistered private schools. (NAN)