BELGRADE, Serbia (AP) — Environmental protesters are once again demanding the cancelation of plans for lithium mining in western Serbia. They took to the streets again Saturday in the Balkan nation, blocking roads and, for the first time, a border crossing. Traffic on Serbia’s main north-south highway was halted by the protests for more than an hour, along with several other roads throughout the country, including one on the border with Bosnia. The road blockade by banner-holding protesters briefly prevented people from crossing the border with Bosnia. Environmental groups want Serbia’s populist government to fully abolish plans by the Rio Tinto company to build a lithium mine in western Serbia. Environmental issues are becoming a rising concern in Serbia due to air, water and waste pollution.