Updated

Greenpeace International says security officers detained four environmental activists opposed to the establishment of an oil palm plantation in Cameroon by a U.S.-based company.

The group said late Friday that Nasako Besingi and three of his co-workers with the environmental group the Struggle to Economize Future Environment were taken from their office in the southwest town of Mundemba on Wednesday. It said they have been held since without charge.

Greenpeace International says the arrests are in violation of Cameroonian law and are linked to their opposition to the oil palm plantation planned by the U.S.-based Herakles Farms.

Herakles Farms, represented by a local affiliate Sithe Global Sustainable Oils Cameroon PLC, began operations in 2010 after signing a contract in 2009 that granted the New York-based firm a 99-year lease on rainforest property.

Palm oil is widely used across Africa.