Thousands of Bolivians have taken to the streets in cities such as the capital, La Paz, angry about the government's recent crackdown on indigenous protesters who opposed a planned highway through a nature reserve.

The demonstrations took place Wednesday, three days after riot police fired tear gas at activists who have spent the past month marching from the city of Trinidad toward the capital to protest the roadway. The police crackdown, in the country's Yucumo area, has led to the resignation of four Bolivian officials, including the defense and interior ministers.

Observers say the fallout from the crackdown has become a challenge for President Evo Morales, who this week announced the suspension of the $415 million construction project until a referendum is held in the two provinces the road will link. Mr. Morales also was critical of the crackdown and he promised an investigation.

Previously, the president 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 nature reserve is home to Amazon Indian groups who have lived in isolation for years. The local people fear outsiders will try to develop the region.

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