A majority of the 22 textbook publishers for public primary and secondary schools in Japan have breached a government rule involving their approval, according to an announcement Friday by the education ministry.

Twelve of the firms showed publications prepared for government review to more than 5,000 teachers and local education officials in violation of censorship regulations, with most of the companies offering cash to nearly 4,000 teachers, according to the ministry.

Following the revelation in October about Sanseido Co., one of the publishers, having shown textbooks then under government censor review to school principals — seeking their opinions in return for cash gratuities — the ministry asked the publishing houses to conduct in-house probes and report the results.