A week-long strike by specialized port workers has held up about 85 grains ships in Rosario port, the biggest agricultural hub in grains powerhouse Argentina, an exporters chamber said.

The crews that guide ships through Argentina's ports and moor them walked off the job last week to demand that more staff be assigned during busy shifts.

Their action forced ships to drop anchor along the country's river ways in the meantime.

Argentina is one of the world's biggest exporters of corn and soy products. Farmers have just started harvesting both crops, however, so shipments are still slow.

The companies whose trade has been disrupted have incurred losses of about $5 million so far, the CIARA-CEC grains exporting group said in a statement. The ships were transporting goods worth more than $400 million, it added.

"International trade has been blocked since the beginning of this month, disrupting fiscal income, hiking costs and causing delays along the entire chain of logistics," the group said.

Argentina forecasts this season's soy crop at 43.5 million to 45 million tons and corn output of 20.5 million to 22 million tons. (Reuters)