A dozen people across Japan were caught cheating on the annual college entrance examinations over the weekend, while heavy snow caused delays to start times in several areas, the organizer said.

All 12 who were caught were disqualified, the most since 2006, the first year when officials began to compile comparable data.

One examinee in Aichi Prefecture was found during the exam looking at textbook images stored on a smartphone. Six in Hokkaido were caught using calculators.

Officials said others used rulers during the math portion, and some altered entries on their computer-scan answer sheets after the exam was over.

The exams, held Saturday and Sunday, marked the start of the annual screening process for students seeking admission to four-year and two-year university courses ahead of the April start of the 2017 academic year.

The number of applicants increased by 12,199 from last year to 575,967, including 471,842 high school students scheduled to graduate in March, accounting for 81.9 percent of all applicants, according to the National Center for University Entrance Examinations, an affiliate of the education ministry.

Amid heavy snowfall, especially in areas along the Sea of Japan coast, on Saturday and Sunday, an unusually large number of venues delayed the start of the examinations. Officials said as many as 10,000 applicants may have been affected.

The portions on geography, history, social studies, the Japanese language and foreign languages were held on the first day. Science and math were covered on the second.

The government began organizing unified exams for national and municipal government-run colleges in 1979 and upgraded them in 1990 so they could also be used by private colleges.