Thousands of people rallied in several towns across Serbia on Monday, demonstrating against a lithium excavation project the Balkan country's government recently signed with the European Union.

The protests were held simultaneously in the western town of Sabac and the central towns of Kraljevo, Arandjelovac, Ljig and Barajevo. They followed similar gatherings in other Serbian towns in recent weeks.

The deal reached earlier this month on "critical raw materials" could reduce Europe’s dependency on China and push Serbia, which has close ties to Russia and China, closer to the EU. German Chancellor Olaf Scholz attended the summit in Belgrade.

However, the deal has been fiercely criticized by environmentalists and opposition groups in Serbia, who argue it would cause irreversible environmental damage while bringing little benefit to its citizens.

The biggest lithium reserve in Serbia lies in a western valley rich in fertile land and water. Multinational Rio Tinto started an exploration project in the area several years ago, which sparked huge opposition and forced its suspension.

Earlier this month, however, Serbia’s constitutional court overturned the government's previous decision to cancel a $2.4 billion mining project launched by the British-Australian mining company in the Jadar Valley, paving the way for its revival.

The Serbian government decided to cancel the excavation plans after thousands of protesters in Belgrade and elsewhere in Serbia blocked major roads and bridges in 2021 to oppose Rio Tinto. Those protests were the biggest challenge yet to the increasingly autocratic rule of Serbian President Aleksandar Vucic.

Vucic has said that any excavation would not start before 2028 and that the government would seek firm environmental guarantees before allowing the digging. Some government officials have hinted a referendum on the issue could also be held.

Protesters who gathered on Monday in Serbian towns said they did not trust the government and would not allow the excavations to go ahead.

"They have usurped our rivers, our forests," said activist Nebojsa Kovandzic from the town of Kraljevo. "Everything they (government) do they do for their own interests and never in the interest of us, citizens." The crowd in Kraljevo chanted "thieves, thieves."

In Sabac, protesters waved Serbian flags and held a march through the town after the rally.