Traffic came to a grinding halt on a highway in the Serbian capital of Belgrade on Saturday as thousands of people blocked the route to protest two new laws on land use.
It's feared the legislation will help foreign companies exploit local resources.
The Serbian government offered mineral resources to companies like China's Zijin copper miner and Rio Tinto.
But environmentalists say the projects will pollute land and water in the Balkan nation.
"After this protest today, everyone should know - whoever is in power in this country - that people must not have their land or water taken away and have their air poisoned."
While Rio has vowed to adhere to all domestic and EU environmental standards, activists say its planned 2.4 billion dollar lithium mine would irreversibly pollute drinking water in the area.
Protesters have already set up similar roadblocks across the country, in a second round of nationwide demonstrations on the issue.
Anger is abound over a referendum that was passed last month making it harder to protest pollution projects.
Protesters are also against a new expropriation law that makes it easier for the state to acquire private land.
The unrest surfaces ahead of parliamentary and presidential elections next year when the ruling Peoples' Progressive Party led by the President Aleksandar Vucic will be seeking re-election.