U.S. beef shipments to Japan may drop after the largest Asian buyer inked a deal with Australia to begin reducing import tariffs as early as next year, the agriculture ministry said.

Japan agreed to gradually lower tariffs on imports of frozen beef from Australia to 19.5 percent and cut duties on chilled beef to 23.5 percent in a bilateral accord reached Monday. The levies are now 38.5 percent, and the reductions will take place over 18 years and 15 years, respectively.

The deal will give Australia an advantage over the U.S. in a market worth ¥267 billion last year, according to Marubeni Research Institute in Tokyo. American beef exporters could lose as much as 80 percent of their sales in Japan unless the U.S. government is able to secure a similar deal, the ministry said.