Australia is set to strengthen its dominance over the U.S. as Japan's biggest beef supplier as a trade deal drives shipments toward a four-year high.

Imports of Australian chilled beef rose 8 percent last quarter and may reach the highest since 2011 while shipments from the U.S. drop to the lowest in three years, according to Tatsuo Iwama, executive director of Japan Meat Traders Association. The rising inflow of Australian meat to Japan's $2.6 billion beef market is the result of decreasing tariffs triggered by a bilateral agreement that went into effect in January, he said.

Australia's expanding market share will spur the U.S. to reach a similar deal with Japan, its biggest beef and pork buyer, according to Makiko Tsugata, an analyst at Market Risk Advisory Co. in Tokyo. The two countries have been in talks for months to strike a bilateral agreement, which would pave the way for the 12-country Trans-Pacific Partnership. U.S. President Barack Obama is seeking fast-track trade negotiating authority from Congress. Senate Democrats staged a last-minute rebellion on Tuesday by blocking a test vote on the trade measure.