SAO PAULO, March 6 (Reuters) - A conveyor belt system collapsed at a grain terminal at the port of Barcarena in northern Brazil, according to a navigation sector source and a soybean analyst on Thursday.

The collapse caused grain shipments to be suspended, the two sources said naming ADM ADM.N and Viterra as responsible for operating the terminal.

ADM deferred questions to the local port authority. Viterra could not be reached for comment.

"The terminal is completely unaccessbile," the navigation sector source said. "It cannot receive grains from barges or load vessels."

The conveyor belt collapsed after being hit by an on-passing barge, according to the navigation sector source. G1, a local media outlet, said a ferry had hit the structure, citing workers present at the scene.

Emergency services rescued eight people, four of whom were injured, the G1 report said. The victims were taken to a municipal hospital and there are not reported casualties, G1 said citing local authorities.

Reuters could not immediately reach Barcarena officials or the local port authority for comment.

(Reporting by Ana Mano and Roberto Samora; editing by David Evans)

((ana.mano@thomsonreuters.com; Tel: +55-11-5644-7704; Mob: +55-119-4470-4529; Reuters Messaging: ana.mano.thomsonreuters.com@reuters.net))