Brazil's main grains port of Paranagua was paralysed on Friday by a strike of 13 unions and was likely to remain at a standstill into the weekend, representatives of workers and the port said.
The strikers, who are insisting on the removal of port administrators, said the work stoppage would go on for an "undetermined period."
The port said 46 vessels were waiting to enter the port and the delay was estimated at about 25 days with another 15 vessels moored in the port unable to load or unload.
Highway police said the line of trucks waiting to unload mostly soy and corn at the port had grown to 60 kilometers (37 miles) and was increasing.
"This afternoon it was decided the paralyzation shall continue for an undetermined period until authorities attend to the demands of Paranagua's maritime community," shipping agent Transcar said in a statement late on Friday.
"Neither the port authority nor state's office showed any good will toward settling the matter," the statement said.
Demonstrators on Friday burned tires, blocked the entrance to the port and marched to the port authority's door.