The main opposition Democratic Party of Japan is considering blocking moves by Prime Minister Shinzo Abe's government to ratify the Trans-Pacific Partnership free trade pact during the current Diet session, a senior DPJ lawmaker said Friday.

The DPJ has compiled a draft report on TPP issues, claiming that Japan's call for the five key farm product categories — rice, wheat, beef and pork, sugar and dairy products — to be exempt from tariff elimination is not sufficiently reflected in the TPP agreement.

But the LDP and its junior coalition partner, Komeito, are expected to take the DPJ to task for flip-flopping over any blockage of the trade pact. Then-Prime Minister and DPJ leader Yoshihiko Noda had been a driving force behind Japan's participation in the multilateral TPP negotiations and announced that it would join them in November 2011.