The Health and Welfare Ministry on Wednesday urged a university professor sitting on the committee that formulates National Dentistry Examination questions to refrain from attending today's committee meeting due to suspicions he had earlier leaked questions.

It was discovered Sunday and confirmed Monday that one question used in the March national exam was similar to a problem in the graduation exams held in January and February for the dentistry department at Ohu University, a private university in Koriyama, Fukushima Prefecture.

Sources close to the health ministry said the committee member in question is a professor at a different university. He has so far denied involvement in the scandal.

However, the Ohu University professor who formulated the school's test identified the committee member as one of two professors who leaked the information to him. The two were members of the committee preparing the March exam, and one of them is still a member of the panel, whose 73 members are currently working on questions for next year's test.

Ministry officials said it would be appropriate for the professor in question to refrain from committee activities given the gravity of the situation.

In addition, a separate Ohu University professor who is also a committee member was called on to refrain from taking part in panel activities, given the fact that the professor teaches at the scandal-tainted university.

Earlier Wednesday, the dean of Ohu University formally acknowledged that a question in the March national exam was leaked to students by a professor and apologized for the scandal.

"I deeply regret that we have tarnished the authority of the national exam and betrayed the trust of examinees and the general public," Dean Kakuitsu Shoji told a news conference.

The university said it would conduct an internal investigation to uncover the facts surrounding the leak.

University officials refused to answer media questions and left the room where the press conference was held.

When the ministry asked the university in June to submit a copy of the graduation exams after getting a tip of the suspected leak, the university submitted one in which the question was deleted in an apparent effort to cover up the leak.

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.

According to university professors, a meeting of the professors of the dentistry faculty was held ahead of Wednesday's press conference, in which senior university officials explained that the leak did not appear to be systematic.