Prime Minister Shinzo Abe said Tuesday he had been listed as an executive member of a school operator run by his friend and received a salary, as opposition parties intensified their offensive against him alleging he favored the operator in connection with a plan to establish a new university department.

The fresh revelation came after a former education ministry bureaucrat admitted last week the authenticity of documents indicating Abe was involved in a government decision to approve the heavily subsidized construction of a veterinary medicine department at Okayama University of Science in western Japan's Ehime Prefecture.

Abe told an upper house committee that for several years more than 20 years ago, he had received a salary of 140,000 yen annually from Kake Educational Institution, whose chairman Kotato Kake is a close friend of his.

"I was in charge of auditing or something else (at the institution) for a couple of years after I was first elected" to the House of Representatives in 1993, Abe said in the House of Councillors Judicial Affairs Committee, adding it was "a long time ago."

Later Tuesday, Chief Cabinet Secretary Yoshihide Suga denied that Abe had influenced the decision on the university project. "Is there anything wrong?" with the prime minister having served as an executive member of the school operator and been compensated for that role, he said at a press conference.

During the parliamentary session, Abe turned down a request from Toshio Ogawa, a lawmaker of the main opposition Democratic Party, to summon to the Diet as a sworn witness Kihei Maekawa, former vice minister of the Ministry of Education, Culture, Sports, Science and Technology, to testify over the documents in question.

The papers showed what appeared to be exchanges between education ministry and Cabinet Office officials tasked with making a decision to open the department in a specially deregulated zone in Imabari in Ehime. Looser rules are applied to such zones as part of the Abe administration's growth strategy.

One of the papers said the timing of opening the department in April next year is "what the highest level of the prime minister's office has said." Another said opening the veterinary department soon was "in line with the prime minister' wishes."

Meanwhile, Democratic Party policy chief Hiroshi Ogushi demanded at a press conference that Hiroto Izumi, an aide to Abe, be summoned to parliament following news reports that he had repeatedly urged Maekawa at the prime minister's office to accelerate preparations to open the new department.

Later in the day, Maekawa confirmed the reports in a statement released through his lawyer. Izumi, who is in charge of specially deregulated zones, had told Maekawa he was making the request on behalf of the prime minister "because the prime minister cannot say it himself," according to the statement.

But Izumi, a former official of the Ministry of Land, Infrastructure, Transport and Tourism, has denied the reports, saying, "It's hardly possible that I especially mentioned Kake Educational Institution and urged him to push ahead the project."

The education ministry is still examining the application filed by the institution to launch the first new veterinary medicine department in Japan in half a century.