A group of university professors urged the government Wednesday not to take part in negotiations on the multilateral Trans-Pacific Partnership free-trade agreement, saying the country may not be able to protect its national interests.

The group submitted to Prime Minister Shinzo Abe, as well as farm minister Yoshimasa Hayashi, a petition against Japan's participation in the negotiations, which now involve 11 nations, signed by over 800 members of the country's academic community.

Satoshi Daigo, a professor emeritus at the University of Tokyo, and Keio University's Masaru Kaneko said Japan's planned participation in the TPP framework may not only harm farming but also alter the medical system and food safety standards.

Although the United States and Japan are expected this week to conclude their preparatory talks for Japan's participation, Kaneko said there is no guarantee that Japan can win "sanctuaries," or exceptions to the TPP's general goal of eliminating tariffs, through the bilateral dialogue.

"We won't know until the very end how (many sanctuaries) we can secure," Kaneko told a press conference.

Even though Abe said after talks with U.S. President Barack Obama in February that joining the TPP talks will not require Japan to commit to completely end all tariffs, Kaneko said Obama cannot guarantee exceptions for products deemed sensitive to Japan if such protections violate U.S. laws.

Tokyo has agreed to allow the United States to retain the tariffs it imposes on automobiles and trucks imported from Japan effectively in exchange for the tariffs Japan imposes on sensitive agricultural produce.