Medan – National exams held at senior high schools in Medan have been marred by cheating involving the schools and students, an NGO says.

Komunitas Air Mata Guru (Teachers' Tears Community), or KAMG, an education-based NGO, said the exams were marred by sophisticated and well-organized cheating techniques.

KAMG chairman Abdi Muskarya Saragih said the NGO had sent monitoring teams to a number of schools. "The teams found several schools in Medan had been mischievous in organizing the exams by having the students come a few hours before the test," he said.

Some students were reported to have arrived in schools at 4 a.m. – four hours before the exams started – which was a sign they might have come to see the test papers, he said. "Some of them copied [the answers] onto mobile phones," he said, adding that KAMG had reported its findings to the National Education Ministry.

Separately, students celebrated the end of the three-day national exam period by drawing graffiti on one another's shirts, on Wednesday. "We are relieved that we have gotten through the exams. We are doing the graffiti to make mementos," David, a student of SMU Immanuel, said.