* Likely to affect containers more than bulk cargo
* Workers object to private terminal's hiring practices
SAO PAULO, July 9 (Reuters) - Dock workers at Brazil's key shipping port of Santos, the largest in South America, are planning a 24-hour strike on Wednesday to protest a port reform recently passed by Congress, a union leader said.
Stevedores were already protesting at the entrance of the port that is near Sao Paulo, the country's largest city, which is on holiday on Tuesday. That resulted in a 3 kilometer (1.86 mile) traffic jam on the highway leading to the port, private road operator Ecovias said on Twitter.
The National Stevedores Association in Brasilia said workers at other ports had decided against a July 10 strike and would instead join a variety of industries in Brazil planning a general strike on July 11, but the Santos union plans to go ahead with a walkout a day earlier.
"We had a meeting yesterday, nothing was accomplished and tomorrow we are going to have a 24-hour stoppage," said Cesar Rodrigues Alves, a senior representative of the union of stevedores at Santos port.
Dock workers are afraid a drive to privatize port terminals under legislation Congress passed on May 16 will lead to a loss of jobs and benefits because private operators would not have to hire through the centralized agency, "OGMO."
They say Embraport, a new $1.2 billion private container terminal on the left margin of Santos owned by local infrastructure group Odebrecht Transport, the United Arab Emirates' DP World and trading company Coimex, is not hiring through OGMO.
The port strike threat comes on the heels of a three-day truck driver protest last week and after nationwide demonstrations that attracted 1 million participants at their peak in late June.
Brazil is currently exporting record soy, corn and sugar crops. Stevedores at Santos held a two-day strike in May, holding up 14 ships mostly carrying containers but having a limited affect on bulk cargo.
Typically, bulk cargo such as soy and corn are less affected by labor stoppages because they require fewer workers. The movement of container goods with perishables such as coffee, bagged sugar and meats are more vulnerable. (Reporting by Caroline Stauffer; Editing by Nick Zieminski)