Bolivia's defense minister has resigned to protest a police crackdown on indigenous groups marching to protest a planned highway through a nature reserve.

Cecilia Chacon said she did not agree with the government's decision to break up hundreds of demonstrators, who began marching toward the capital, La Paz, from the city of Trinidad last month to show their opposition to the project.

On Sunday, riot police fired tear gas at the marchers who had gathered in the Yucumo area. They rounded up several protesters, who were later released after area residents blocked an airport landing strip to prevent authorities from flying the detainees home.

The demonstrators say the $415 million road threatens a protected area and that their right to be consulted was violated.

President Evo Morales has angered indigenous people by saying the road would be built through the Isiboro-Secure Indigenous Territory National Park “whether they like it or not.” Activists have said they will be ready with bows and arrows when the time comes to protect their land. The project will be financed in part by the Brazilian government.

Mr. Morales is Bolivia's first indigenous president. In past speeches, he has said all nations must respect Mother Earth in their environmental policies.