BEIJING, Oct 13 (Reuters) - China's soybean imports rose in September as previously delayed cargoes at customs started rolling in, and are forecast to remain robust in the months ahead due to higher arrivals from the United States as part of the Sino-U.S. trade deal.

Demand for the oilseed is expected to stay strong in the world's top soybean importer due to a pig herd that is recovering rapidly from the African swine fever.

China brought in 9.79 million tonnes of soybeans in September, up 1.9% from 9.6 million tonnes in August, according to data from the General Administration of Customs released on Tuesday.

The figures were also up 19% from 8.2 million tonnes in September last year, the data showed.

"Some cargoes were delayed earlier and cleared customs in September," said Xie Huilan, analyst with agriculture consultancy Cofeed. "The shipments were still mainly from Brazil."

Crushers had been ramping up imports of Brazilian beans earlier on good crush margins, and large arrivals of the oilseed in the past few months have pushed inventories in China to record high levels.

Exports from Brazil had picked up after March as the weather there improved. Shipments from the South American country were seen shrinking, however, as the harvest there approached its end.

China also booked large volumes of U.S. soybeans but mainly for delivery in the new market year (September to August), partly to fulfill its pledge under the Phase 1 trade deal the two countries signed in January this year.

American cargoes were expected to increase next month, and continue to rise in the next few months, analysts said.

National weekly soybean meal inventories in China were at 994,500 tonnes as of Oct. 11, down after hitting a record high 1.27 million tonnes at end of August.

Soybean inventories were at 7.12 million tonnes as of Oct. 11.

China, the world's top producer of pigs, has been working to boost output after the deadly African swine fever outbreaks, first discovered in the country in August 2018, decimated its massive herd.

Soybean imports surged 15.5% year on year in the first nine months of 2020 to 74.53 million tonnes.

Imports of vegetable oils in September were 921,000 tonnes, down 5.6% from the previous month.

For more details, click on (Reporting by Hallie Gu and Shivani Singh; Editing by Muralikumar Anantharaman)