About 700 persons who say they used to extract gold from what is now Parque Nacional Corcovado threaten to block highways if they are not compensated.
The former gold panners say they want special handling of a measure that will give each of them 5 million colons, about $10,000.
They are getting support from the Asociación Nacional de Empleados Públicos y Privados, which reported their plight.
Corcovado became a national park more than 20 years ago, and gold extraction was prohibited, even though illegal panning goes on now.
At the time, between 1986 and 1992 some 350 former gold miners were paid off some 200,000 colons each, The 700 say they should have been paid too. The money would come from the Ministerio de Ambiente y Energía.
Among the roads they threaten to block if they do not see action is the Interamericana Sur.