WASHINGTON – A group of U.S. agricultural organizations has urged Japan to lift tariffs on sensitive farm products to secure the Trans-Pacific Partnership free trade pact, according to a document made available to Thursday.

The American Farm Bureau Federation and 16 other organizations said it will be “ultimately difficult” to support a TPP agreement unless Japan eliminates such tariffs, in a letter they sent to U.S. Trade Representative Michael Froman on Wednesday.

The group took the action after seeing the U.S. and Japanese governments remain apart over the market access issue in their bilateral talks earlier this month in Singapore on the sidelines of the ministerial meeting on the TPP.

Japan has said it must keep tariffs in place for five “sacred” categories — rice, wheat, beef and pork, dairy products and sugar — in the negotiations on signing the U.S.-led pact with the United States and 10 other countries.

“If Japan continues to insist on unreasonable protections to a range of agricultural categories, we ask you to consider concluding the TPP without Japan,” the letter said.

The group said any trade pact that includes such special treatment for a rich developed country like Japan is “unacceptable.”

The 12 negotiating countries have given up trying to achieve the goal of concluding the TPP by the end of the year at the Singapore talks, and set their sights on continuing the negotiations next year.