Heated debate raged late Wednesday as the Democratic Party of Japan discussed whether Japan should join the Trans-Pacific Partnership free-trade accord talks, with Prime Minister Yoshihiko Noda trying to hammer out a decision before the Asia-Pacific Economic Cooperation forum summit this weekend.

After weeks of intense internal debate, tempers flared at the DPJ's final meeting that started earlier in the evening, as anti-TPP lawmakers made a last-ditch effort to stop Japan from joining the free-trade pact.

Former farm minister Masahiko Yamada, who heads a group of lawmakers against the TPP, said he wouldn't give up the fight and submitted a petition to the government with the signatures of 200 DPJ anti-TPP lawmakers.

"We must stop (Japan from joining the TPP talks) at any cost," he said during a meeting with like-minded lawmakers.

Noda is expected to announce Thursday that Japan will participate in the talks, joining nine countries including the U.S. and Australia.

"I am aware there are various opinions, but once the discussions have matured, I think it is necessary to come to a conclusion," Noda told a session of the Lower House Budget Committee.

The free-trade pact has triggered harsh criticism from not only the opposition parties but also from DPJ lawmakers, as it aims to eliminate all tariffs among member states within 10 years.