BEIJING- China's soybean imports from Brazil almost halved from the previous year, customs data showed on Monday, as importers held off purchases amid hopes of a Sino-U.S. trade deal and as a severe African swine fever outbreak curbed demand.

China, the world's top buyer of soybeans, imported 3.793 million tonnes of the oilseed from Brazil, its largest supplier, in October - down 42% from 6.53 million tonnes in the year-ago month, data released from the General Administration of Customs showed.

"In August and September, many importers were waiting to buy U.S. soybeans, and missed the chance to buy Brazilian beans," said a trader based in China.

"That has affected arrivals in October and November," said the trader, who declined to be named as he was not authorized to speak with the media.

China's October imports of soybeans from the United States, meanwhile, came in at 1.147 million tonnes, up from just 66,955 tonnes a year ago, according to the data, as cargoes booked during a Sino-U.S. trade truce arrived.

China typically buys most of its soybeans from the United States in the fourth quarter, when American shipments dominate the market after the U.S. harvest and as Brazilian crops are still maturing.

Beijing slapped hefty tariffs on a list of U.S. products including soybeans in July last year after the trade war broke between the world's top two economies. U.S. soybean shipments to China gradually slid to a halt as a result, before picking up again after the two sides agreed a truce in December.

China has bought more U.S. soybeans in recent months, as a goodwill gesture amid ongoing talks. 

A year-long outbreak of African swine fever that has swept through the country has also curbed imports.

China's pig herd shrank by 41% in September versus a year ago, according to official data, reducing demand for soymeal, a key ingredient in animal feed. 

(Reporting by Hallie Gu and Shivani Singh Editing by Shri Navaratnam) ((Hallie.Gu@thomsonreuters.com; +86 10 6627 1250; Reuters Messaging: hallie.gu.thomsonreuters.com@reuters.net))