BELGRADE, Dec 4 (Reuters) - Thousands of people blocked roads across Serbia in an anti-government protest against two new laws that environmentalists say will let foreign companies exploit local resources. Serbia"s government has offered mineral resources to companies including China"s Zijin copper miner (601899.SS) and Rio Tinto (RIO.L). Green activists say the projects will pollute land and water in the Balkan nation. The protest is a headache for the ruling Peoples" Progressive Party led by the President Aleksandar Vucic ahead of parliamentary and presidential election next year. Thousands gathered on the main bridge in the capital Belgrade chanting "Rio Tinto go away from the Drina River." They held banners reading: "Stop investors, save the nature," "We are not giving away the nature in Serbia," and "For the land, the water and the air". Roadblocks have been set up all over Serbia including the second largest city of Novi Sad, in Western Serbia in Sabac, Uzice, and Nis in the South, in Zajecar in the East. "The reason (for the protest) is to protect our land, water and air. We do not want it to be sold cheaply," said Stefan, a student protesting in Belgrade. Rio has promised to adhere to all domestic and EU environmental standards, but environmentalists say its planned $2.4 billion lithium mine would irreversibly pollute drinking water in the area. The protesters are angry about a referendum law passed last month which will make it harder for people to protest against polluting projects, as well as a new expropriation law, which makes it easier for the state to acquire private land. President Aleksandar Vucic on his Instagram profile published a picture from the village of Gornje Nedeljice where Rio Tinto have already started buying land for its future lithium project. Vucic said once the environmental study on the project is complete, he would call a referendum to allow people to decide whether the project should go through. "Everything we build today we are leaving to our children," Vucic wrote on Instagram. (This story corrects figure in paragraph 8 to $2.4 billion instead of 2.4 million)