TOKYO (Reuters) - Japan’s education ministry on Thursday it had found documents that could back up opposition parties’ suspicion that Prime Minister Shinzo Abe used his influence to unfairly help a friend set up a business.

An aerial view shows the site where Kake Educational Institution is scheduled to build a new veterinary department of a private university, in Imabari, Ehime Prefecture, Japan, in this photo taken by Kyodo May 17, 2017. Mandatory credit Kyodo/via REUTERS

Abe has repeatedly denied abusing his authority to benefit his friend and his grip on power is not in danger. But the affair has chipped away at Abe’s support, according to opinion polls, and it looks unlikely to fade away.

“I am taking this result seriously,” Education Minister Hirokazu Matsuno told a news conference, referring to the unearthing of the documents during a second investigation, after an initial one found nothing.

The Asahi newspaper reported last month that it had obtained documents showing that the Cabinet Office had told the education ministry that Abe wanted a new veterinary school run by a friend to be approved.

The report led to opposition questions about the process by which the government decided to allow a veterinary department to be set up in a state special economic zone, since the government has not approved such departments in decades because of concern about a glut of veterinarians.

Opposition politicians and the media have identified Abe’s friend as Kotaro Kake, the director of the Kake Educational Institution, which wants to open the veterinary department.

An official at the institution declined to make immediate comment on Thursday, and Kake was not available for comment.

The Kake Educational Institution issued a statement last month saying it was following the procedure necessary to set up a veterinary department and it abided by the law.

Abe told parliament that being a friend of the school operator did not mean he had helped the institution get permission to open a new school.

The affair is Japan’s second political controversy linked to a school in recent months. In the other case, an educational group with ties to Abe’s wife got what critics said was a favorable land deal to build a school.

Abe’s wife, Akie, and Abe denied any wrongdoing in connection with that case.

A voter survey by public broadcaster NHK showed on Monday that 48 percent of those polled said they supported the Abe government, down three percentage points from a month ago, while the disapproval rating for the government rose six percentage points to 36 percent.