(Updates with walkout of replacement workers)
BUENOS AIRES, June 19 (Reuters) - Grain cargo ships in Argentina's main shipping hub of Rosario were halted late on Monday when replacement workers filling in for striking unions walked off the job after receiving threats, the country's export chamber said.
Regular port workers were on the fifth day of a wage strike on Monday when replacement workers were brought in early in the day, allowing for the resumption of some loading of freshly harvested corn and soy.
"New problems came up, including threats and intimidation, so work was halted," Andres Alcaraz, spokesman for Argentina's CIARA-CEC export companies' chamber, told Reuters by telephone.
Some 80 percent of Argentine grains output is shipped through the Rosario port system.
On Thursday some 20 ships were prevented from moving due to the strike by members of the CGT San Lorenzo port workers union.
Industry giants like Cargill and Bunge have crushing plants and terminals in the region.
Edgardo Quiroga, head of the San Lorenzo delegation of the CGT, said the strike would continue and the union would block access to port terminals. (Reporting by Maximilian Heath; Writing by Caroline Stauffer and Hugh Bronstein; Editing by Jeffrey Benkoe and Sandra Maler)