* Container ships worst affected by the stoppage
* Reason for strike, planned duration not clear
* Potential for delay to coffee, sugar shipments
SAO PAULO, May 30 (Reuters) - Stevedores at Brazil's largest port, Santos, went on strike on Wednesday, threatening delays to shipments of coffee, sugar and other commodities and manufactured goods, the port authority said.
A port spokesman could not immediately confirm the reason for the strike nor its planned duration but said it mostly affected container ships while loading of liquid cargoes was continuing as normal.
Senior representatives from the stevedores' association were not immediately available for comment. They are expected to meet on Wednesday morning to discuss the stoppage, one shipping operator said.
Brazil is the world's No. 1 producer of coffee and sugar and the harvest for both is in its early stages. Most sugar is exported in bulk while coffee is bagged up and packed into containers.
In the past, the stevedores' association at Santos has tended to stage 24-hour warning strikes and threatened to proceed to unlimited stoppages unless their grievances were addressed in negotiations.
Santos is a key exit point for the country's most valuable farm commodities like soy as well sugar and coffee. (Reporting by Roberto Samora; Writing by Peter Murphy; Editing by Kenneth Barry)