CAMPINAS, Brazil- Brazilian agricultural commodities exports are forecast to rise to as much as $102 billion this year, driven by a growing world urban population and resilient demand from China, which is embroiled in a trade spat with the United States.

The country's agricultural exports were $96 billion in 2017, Luiz Cornacchioni, head of a farmer group known as Abag, told an industry event on Tuesday.

But he cautioned Brazil needed to build on its strengths in order to continue leading exports markets for products like soybeans, coffee, orange juice and chicken.

Brazil's farmers face multiple challenges, he said, including dealing with government-controlled freight prices and historic logistical bottlenecks.

These may compromise their ability to compete in global markets as well as impact the outlook for the sector, which accounts for 23.5 percent of Brazil's gross domestic product and generates about one-fifth of the jobs in the country, according to Cornacchioni.

Although Brazilian farmers benefited from recent global trade tensions which helped local soybean exporters, a truce announced by Washington and Beijing last weekend may affect Brazil's trade prospects going forward.

"Rising U.S. soybean stockpiles sparked the truce with China on trade," Cornacchioni said. "They have nowhere to put it."

(Reporting by Ana Mano Editing by Edmund Blair and Bernadette Baum) ((ana.mano@thomsonreuters.com; Tel: +55-11-5644-7704; Mob: +55-119-4470-4529; Reuters Messaging: ana.mano.thomsonreuters.com@reuters.net))