BELGRADE, Serbia (AP) — Serbian eco-activists on Thursday set up several tents in central Belgrade, pledging to camp there to press for their demand for a ban on lithium mining in the Balkan country.

The tent protest in a park outside the Serbian presidency building is part of a wider environmental movement that has rattled the populist authorities ahead of April elections.

Several hundred people on Thursday also rallied outside President Aleksandar Vucic’s headquarters, before marching toward the government building.

“We have one clear demand — a law which should forbid exploring borate and lithium,” activist Savo Manojlovic of the Kreni-Promeni, or Go-Change, group told The Associated Press.

Used in batteries for electric cars, lithium is considered one of the most sought-after metals of the future as the world shifts to more renewable energy sources.

Activists in Serbia, however, say that lithium mining would present a major hazard for the environment. A plan by Rio Tinto mining company to open a lithium mine in western Serbia has triggered road blockades, forcing the government to announce it was scrapping the project.

Manojlovic and others now insist that authorities must pass a law to ensure that there will be no lithium mining by Rio Tinto or any other company.

The tent protest, he explained, is meant to symbolize how people will be forced to leave their homes and villages wherever mines open in Serbia.

“After the election, maybe Rio Tinto will be back,” said Manojlovic. “We don’t know that If we don’t have the law.”

Zlatko Kokanovic, an activist from lithium-rich western Serbia who traveled to Belgrade for the protest, told the AP that Rio Tinto has not left the region but has hired new people instead.

Serbia also faces scores of other environmental problems, from waste management to air and water pollution.

The country must tackle the accumulated problems in order to advance toward membership in the European Union.

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