Marchers opposed to a highway that Bolivia plans to build through an indigenous-inhabited nature preserve have briefly detained the foreign minister in the country's eastern lowlands.

Foreign Minister David Choquehuanca says protesters obliged him to march with them out of fear they would be attacked by police or pro-government activists. He had arrived in the area to mediate the dispute.

Interior Minister Sacha Llorenti called Saturday's action a "hostage-taking."

A march on La Paz by Amazon Indians who say the Brazil-funded highway will destroy their hunting and fishing grounds in the Isiboro-Secure preserve has been paralyzed for 10 days.

President Evo Morales has alienated many core supporters by insisting on the highway.