Prime Minister Shigeru Ishiba on Friday signaled his readiness to speak before a Diet political ethics panel over his controversial distribution of gift vouchers to new lawmakers of his ruling Liberal Democratic Party.

"I am sincerely explaining here, but if you are not convinced, I would go to another place," Ishiba said at a meeting of the House of Councillors Budget Committee, in response to a question from Takumi Shibata, a lawmaker of the opposition Nippon Ishin no Kai.

Over the gift voucher issue, Yoshihiko Noda, leader of the main opposition Constitutional Democratic Party of Japan, and Yuichiro Tamaki, head of the Democratic Party for the People, have called on Ishiba to give explanations before a parliamentary ethics panel.

The LDP has rejected the opposition demand, claiming that the distribution of gift vouchers did not violate the political funds control law, unlike the high-profile political funds scandal involving LDP factions.

Still, LDP Diet affairs chief Tetsushi Sakamoto said that the prime minister has to attend an ethics panel meeting if such a meeting is held.

At Friday's Upper House budget committee meeting, Taiga Ishikawa of the CDP argued that former Prime Minister Fumio Kishida, Ishiba's immediate predecessor, also gave gift vouchers to LDP lawmakers while in office, and questioned whether this was a common practice of the LDP.

Ishiba said that he had heard of that matter but had not confirmed it. The prime minister also said that he had decided to give the gift vouchers on his own.

Hideya Sugio, another CDP lawmaker, asked Ishiba whether he had used the Cabinet Secretariat's secret funds to purchase the gift vouchers, but the prime minister reiterated that he had used his own money.