China has bought at least 14 cargoes of US soybeans, two traders with knowledge of the deals said, its largest purchase since at least January and the most significant since a summit between presidents Xi Jinping and Donald Trump in October.

China is buying US soybeans to meet the pledges it made to Washington at the trade summit in Busan, South Korea, even though the cargoes purchased on Monday are priced higher than rival Brazilian offers, two Asia-based traders said.

"This bigger round of US soybean buying is no longer a goodwill gesture but a manifestation of China's commitment to the Busan terms," said a Singapore-based trader.

China's state-owned grain trader Cofco bought at least 840,000 tonnes for shipment in December and January, two traders with knowledge of the deals said.

Eight of the vessels were for shipment in December and January from US Gulf Coast terminals, while the rest were for shipment in January from Pacific Northwest ports, one trader said. A second trader estimated around 75 percent of the sales were for Gulf shipment, with the remainder from the Pacific Northwest ports.

The sales total may ultimately be larger if more deals are finalized, traders said.

The White House said China had agreed to buy 12 million tonnes of US soybeans this year, but only a small volume of sales had occurred before Monday. China imported nearly 27 million tonnes of US soy last year, according to U.S. government data.

Asian traders estimated Cofco paid US$2.35 to US$2.40 per bushel over the January Chicago contract for shipments from Gulf terminals and a premium of US$2.15 to US$2.20 per bushel from Pacific Northwest ports, well above the prices for Brazilian new-crop soybeans, which are around US$1.25 per bushel over Chicago Board of Trade futures.

"It is a political move, as prices being paid by Cofco are much higher than Brazilian prices," said a trader at a company which runs soybean processing plants in China. "Chinese companies are just doing it as a commitment to buy US soybeans."

Trump said on Friday sales would be on track by the spring.

"It is good to see the hard work of our US trade negotiators and their Chinese counterparts turning into business for US soy farmers and exporters. We look forward to this continuing as trade lanes are restored," said Jim Sutter, chief executive of the US Soybean Export Council.

China had largely shunned US soybeans this season due to a heated trade war with Washington, sourcing supplies from export rivals Brazil and Argentina instead.

The absence of their top customer dragged US soy prices to near multi-year lows this summer and heaped strain on a farm economy already struggling from rising costs for inputs like fuel, fertilizer and seeds. Farmers and trade groups have been working to open new markets for US soy, but those efforts to replace Chinese demand have been difficult.

US soybean futures on the Chicago Board of Trade rallied nearly 3 percent on Monday to a 17-month high on the China trade optimism. (Reuters)