According to people familiar with the sales, Chinese private soybean producers purchased around five cargoes from the U.S. this week, less than the market anticipated.

In the world's largest soybean importer, the private crushers purchased the cargoes for shipment in December and January, the people said, requesting not to be named as the matter is personal.

Notwithstanding Beijing granting concessions on some U.S. beans for retaliatory tariffs, the sector has been frustrated by the rate of purchases.

According to Monica Tu, an oilseed analyst at Shanghai JC Intelligence Co., deals reported for delivery from the US in January may only be 10 percent to 15 percent of what the industry predicted.

"Buyers were wary," Tu said, adding that they are happy nonetheless with the contradictory data on trade issues between China and the US.

Still, American soybean's competitive market prices compared to rival supplies like those coming from Brazil may have led to renewed imports, while optimism that profits from crushing soybeans in China will rise after the Lunar New Year may have helped spur them on too, Tu said.

Reuters reported earlier that for December and January this week, Chinese commercial importers bought as many as seven U.S. soybean cargo shipments at competitive U.S. prices.

China's oilseed purchases from the U.S., the world's second-largest producer, are regarded as a bargaining barometer. A U.S. request for China to detail how the country aims to hit as much as $50 billion annually in agricultural exports has become a sticking point in talks on a phase one trade deal, according to people familiar with the issue.

China has also taken steps that could show the risk of exports of U.S. agricultural goods if the talks are unpleasant. Although China has resumed purchases of some agricultural products as talks advanced, the unloading of American soybeans at its ports is now slowing, the people added, which could slow down more purchases.

Meanwhile, approximately 1.8 million tons of soybeans are stored in China's ports, mostly for government reserves. Local buyers have to pay a heavy deposit to customs before they can collect refunds on China's 30 percent tit-for-tat tariffs due to the trade showdown. Deposits can pay up to 60 million yuan ($8.5 million) per freight and can take about 28 days to unload.

China's Ministry of Commerce and General Customs Administration did not respond immediately to faxes seeking comment, respectively, on the enforcement mechanism and port delays.