The TPP would be a regional trade bloc, consisting of Australia, Brunei, Chile, Malaysia, New Zealand, Peru, Singapore, the United States and Viet Nam.

"The US pork industry strongly supports Japan’s entry into the TPP, and NPPC urges the United States and the other TPP countries to accede to Japan’s request," said NPPC President Doug Wolf. "Pork producers would gain tremendous market opportunities with Japan as part of the TPP."

Japan already has free trade agreements with six of the nine TPP countries: Brunei, Chile, Malaysia, Peru, Singapore and Viet Nam.

Japan is the No. 1 market for the US pork industry, which in 2010 exported $1.65 billion of pork to the Asian nation and which in the first nine months of this year has shipped $1.44 billion.

"Japan is our top market, but that market can be expanded through the TPP," Mr Wolf said. "And expanding existing markets and opening new ones are vital to the continued profitability of US pork producers."

The US pork industry last year exported nearly $4.8 billion of pork, an amount that added about $56 to the price producers received for each hog marketed.