But a US shrimp lobby group pressing for the tariffs, the Southern Shrimp Alliance, termed Thailand's boycott threat "economic terrorism" and told the government not to bow to the demands of the soybean industry.

The American Soybean Association (ASA) in a letter to Secretary of Commerce Donald Evans said the outcome of a shrimp antidumping petition against Thailand as well as China, Vietnam and India could have "a direct and serious impact" on the local soybean industry.

The ASA was particularly concerned over a threat by nine private trade groups in Thailand, representing virtually all business consumers of US soybean exports, that "have agreed to ban imports of soybeans and soybean meal" if the Commerce Department imposed antidumping duties on Thai shrimp.

"US restrictions on frozen shrimp, a primary export from a number of countries involved, have the very high potential to alienate the very customers that are so valuable to US soybean exporters," ASA President Neal Bredehoeft said in the letter, according to the Shrimp Industry Task Force on Thursday.

The task force is a coalition of seafood importers and restaurants that complained the duties would force higher shrimp prices and hit consumers.

ASA also warned that the duties could lead to lost business by soybean farmers and exports of American soybean products to Asia.

Among the four countries, China is a top importer of soybeans from the United States, taking in 8.29 million tonnes last year, an increase of nearly 100 percent over the previous year, valued at 2.2 billion dollars.

"Large quantities of soybean meal are used as feed for farm-raised shrimp in these countries, and a great deal of that is produced from soybeans exported from the United States," Bredehoeft said.