TOKYO (Kyodo) -- Fresh evidence emerged Friday pointing to a long-standing controversial practice among Japanese premiers from the Liberal Democratic Party of distributing gift certificates to party lawmakers, with a lower house member of the party saying he received vouchers after being elected in 2012 when Shinzo Abe was premier.

Toshitaka Ooka became the latest parliamentarian to come forward, saying he received around 100,000 yen ($670) worth of vouchers within "a few months" of the House of Representatives election in December 2012.

The revelation contrasts with incumbent Shigeru Ishiba's statement in parliament that he had "no knowledge" of such gift-giving by prime ministers taking place as a long-standing routine practice.

It also came as a new blow to the LDP, which has been struggling to restore public trust eroded by a separate slush funds scandal.

Donations to politicians by individuals for the purpose of political activities are banned under Japanese law. Ishiba has admitted to handing out gift vouchers but has maintained that there are no legal problems because they were meant to show "appreciation" for his fellow LDP members and were not donations.

But Ishiba has acknowledged that the practice was out of synch with public sentiment at a time when households are reeling from the pain of inflation. He told parliament that he would speak before the political ethics committee of the Diet if formally requested.

Ooka said he received the vouchers when he met with Abe over dinner with other first-term lower house members at the prime minister's official residence. The lawmaker said he does not remember exactly who delivered the vouchers, but that it was not Abe himself.

Ishiba admitted to handing out vouchers worth 100,000 yen each to rookie lower house lawmakers of his party when they had a dinner meeting at his official residence on March 3.

Abe held at least five dinner meetings with new lower house members between March and June of 2012, records show. Ishiba attended one of those meetings, held in March, as then secretary general of the LDP.

"I thought the party paid for (the vouchers), just like a company rewarding a hard-working employee," Ooka said. He confirmed the details with reporters on Friday.

The 2012 general election opened the way for Abe to become postwar Japan's longest-serving prime minister. After a short stint between 2006 and 2007, he remained in power between 2012 and 2020. He was gunned down during an election campaign speech in 2022.

Also facing increasing scrutiny is Ishiba's predecessor Fumio Kishida. Kishida has been found to have distributed gift certificates, worth 100,000 yen each, to parliamentary vice ministers on the occasion of a dinner meeting in December 2022. His office has said no laws were broken.

The series of revelations follow a comment made Sunday and later retracted by an LDP lawmaker who said giving gift vouchers was "standard practice" for premiers. Opposition parties have been stepping up pressure on the ruling party as the latest controversy follows on the heels of the slush funds scandal.

Yoshihiko Noda, who leads the main opposition Constitutional Democratic Party of Japan, has been urging Ishiba to explain himself before the political ethics committee. He was prime minister between 2011 and 2012, but has said he "never" distributed vouchers while in office.

The LDP lost majority control of the lower house with its ally Komeito in October, partly as a result of the slush funds scandal, in which party factions distributed to members money in excess of their targets for the sales of tickets to party fundraising events. As head of a minority government, Ishiba has vowed to secure support from the opposition camp as broadly as possible.

Komeito chief Tetsuo Saito said the LDP should "break the chain of bad habits." During a press conference, he said no Komeito lawmakers who served as parliamentary vice ministers under Kishida received vouchers.

Among other recent prime ministers, the office of Yoshihide Suga, Abe's immediate successor, has revealed that "souvenirs" were distributed but insisted that no laws were broken.