(Adds 12 truckers arrested for extortion, throwing grains on road)
BUENOS AIRES, Feb 9 (Reuters) - Some 93 cargo ships were waiting on Friday to load soy and corn from Argentina's main exporting hub of Rosario, more than a week into a truck owners strike, the spokesman for an industry group said.
That was up sharply from just over 60 on Thursday, said Andres Alcarez, spokesman for export company chamber CIARA-CEC.
Truckers owners went on strike last week in a bid to force the adoption of mandatory minimum grains hauling rates. The work stoppage also slowed the unloading of beans at soyoil and meal manufacturing sites.
They appeared to be growing more aggressive on Friday, and Argentina's security ministry said in a statement 12 truckers had been detained for using "extortionist methods" and "throwing large quantities of grain in the road."
Police made the arrests in Buenos Aires province, Argentina's main grains belt. The 12 were protesting in the town of Carlos Casares, and had also seized seven trucks, four cars and a motorbike, the ministry said.
Argentina is the world's top exporter of soybeans and soymeal and the No. 3 exporter of both corn and soymeal. Some 80 percent of Argentina's agricultural exports depart from Rosario. (Reporting by Maximilian Heath and Eliana Raszewski, writing by Caroline Stauffer; Editing by Marguerita Choy and David Gregorio)