Schools have been threatened with closure if they cannot put an end to inter-school rivalry that has led to student violence. The Education Ministry says 12 schools with a record of violence have been placed on a blacklist which will be watched closely. Minister Sukavich Rangsitpol said teachers must enforce regulations to control students. They have been given until next month, or schools will be closed. Inter-school rivalry, mostly between technical colleges and vocational schools, late last month left a 15-year-old boy shot dead on a city bus. Deputy Prime Minister General Chavalit Yongchaiyudh has declared a 'cultural war' against Western influences he believes are affecting Thai society.