SAO PAULO, May 10 (Reuters) - Privately owned Brazilian soy crusher and soy byproducts exporter Bianchini was forced to halt operations at its Canoas plant in Rio Grande do Sul amid severe flooding, Corporate Director Gustavo Bianchini told Reuters on Friday.

He said management plans to resume production at the plant when waters, which they estimated were currently between 30 cm and 70 cm high, recede.

An adjacent warehouse with 100,000 tons of soybeans was also flooded, and it is unclear how much product can be saved, according to the executive. He noted the water made the grain swell up inside the structure, making it "double in size" when the water was at its highest.

The situation compromised the walls of Bianchini's storage facility in Canoas, the executive said. He confirmed the authenticity of a picture circulating on social media that showed soybeans pouring from the breaking walls.

Bianchini said the affected warehouse can hold about 400,000 tons of grains, adding it was not entirely full.

"It could have been much worse," the executive said by telephone.

The company's Canoas plant has the capacity to process 2,500 tons of soybeans per day, while its Rio Grande unit crushes 3,400 tons, he said. (Reporting by Ana Mano; Editing by Chizu Nomiyama and Jan Harvey)