The move highlights the growing impact of the trade dispute between the United States and China even after Beijing agreed to a potential removal of tariffs on some soybean imports.

Columbia Grain Trading stopped new sales from 24 July, a spokesman at Marubeni, one of Japan's biggest trading houses, told Reuters.

The decision does not impact other Marubeni units such as Gavilon involved in trading grains, including soybeans to China, and their business continues as normal, the spokesman said.

There are no plans to shut down Columbia Grain Trading, the spokesman said.

China was the top buyer of US soybeans until Beijing slapped a 25 percent tariff on shipments in response to US tariffs on a range of Chinese products.

That all but halted US soybean imports, dealing a blow to American farmers and traders of the oilseed across the sector.

But as talks have restarted between the US and China on trying to resolve their issues, Beijing indicated it would allow exemptions to the soybean tariffs for some cargoes arriving before the end of the year.

China's demand for soybeans crushed into livestock feed has decreased dramatically in recent months as African swine fever swept across the country, resulting in the death or culling of millions of pigs.

China brought in 16.6 million tonnes of soybeans from the United States in 2018, about half of the 32.9 million tonnes purchased the year before, as the tariffs curbed buying.

Marubeni executives have said slumping grain prices and shrinking trading volumes weighed on the company's US grain business because of the trade war.