A question contained in the National Dentistry Examination conducted in March was leaked to dentistry department students at Ohu University, a private university in Koriyama, Fukushima Prefecture, Health and Welfare Ministry officials said Monday.

The same question was included in the graduation exams of the department held between January and February, the officials said.

The ministry, after receiving a tip about the alleged leak, asked the university in June to submit a copy of the graduation exams. The university submitted one in which the leaked question was deleted in an apparent effort to cover up the leak, the officials said.

But the university later told the ministry that a professor who was in charge of holding the graduation exams confessed he had obtained the content of the question from two professors at two different universities.

The professor also admitted he had altered the exam sheet in question before submitting it to the ministry, the ministry officials said, quoting university officials.

The ministry is considering filing criminal complaints with police against those involved in the alleged leak, according to the officials.