Prosecutors will reopen an investigation into former Prime Minister Shinzo Abe over his camp's spending of millions of yen for dinner receptions held for supporters after an inquest body decided that prosecutors' earlier decision not to indict him was inappropriate, according to the body's statement released Friday.

The decision dated July 15 by the Committee for the Inquest of Prosecution relates to allegations of endowments under the public officers election law as well as failure to fulfill a duty of care in selecting and managing accounting officers under the political funds control law.

File photo taken in April 2016 shows Japanese Prime Minister Shinzo Abe (C) posing with guests invited to a cherry blossom-viewing party at Shinjuku Gyoen National Garden in Tokyo. (Kyodo) ==Kyodo

The former premier "must fulfill his responsibility to provide explanations about any suspicions" instead of holding his secretary entirely responsible, the decision said.

Abe told reporters Friday he will wait to see how the investigation proceeds, saying the prosecutors' original decision not to indict him was the result of a properly conducted investigation.

"I and my office have made sincere efforts to fully cooperate with the investigation," Abe said.

Opposition parties urged Abe to appear in the Diet as a sworn witness.

The body's decision shows that "Abe himself was obviously involved," said Jun Azumi, Diet affairs chief of the main opposition Constitutional Democratic Party of Japan.

The Tokyo Public Prosecutors Office's special investigations unit decided last year not to press charges against Abe over the scandal because of insufficient evidence.

In the case, Hiroyuki Haikawa, one of Abe's state-paid secretaries, was fined for failing to report some 30 million yen ($274,000) related to the dinner functions that needed to be reported in the political funds reports between 2016 and 2019.

Since the scandal came to light in 2019, the former premier has repeatedly denied in parliament the allegation that a group managing his political funds partially covered the costs of the receptions.

After the prosecutors decided not to press charges in December, Abe said he had no knowledge of any problems with his camp's bookkeeping but apologized for repeatedly denying the accusations which turned out to be true.

Haikawa headed the group of the prime minister's supporters that hosted the receptions at two luxury hotels in Tokyo between 2013 and 2019 on the eve of the government-sponsored annual cherry blossom viewing parties.

The events cost 23 million yen over a five-year period through 2019, much higher than the amounts collected from attendees, many of whom were voters in Abe's constituency in Yamaguchi Prefecture, western Japan.

To make up for the shortfalls, Abe's side is believed to have paid a total of 9 million yen over the five-year period. But the supporters' group and the former premier's fund management body did not record the income and expenditures in their political fund reports, in violation of the political funds control law.