Rio Tinto is worried about the Serbian prime minister's comments on its lithium project or considering suing Serbia.

Rio Tinto's chief executive said on Tuesday that in his first speech since Belgrade revoked the global mining company's exploration license, he said he was concerned about the Serbian prime minister's comments on the company's lithium project.

Serbian Prime Minister Anna Burnabic gave in to environmentalists, halted Rio Tinto's lithium project last week and accused Rio of providing insufficient information to the community about the project.

"We are obviously very concerned about the prime minister's remarks," Jacob Stausholm, chief executive of Rio Tinto, said in an interview.

Stausholm was speaking after the company reached an agreement with Mongolia to end a long-running dispute over the $6.925 billion expansion of the Oyu Tolgoi copper and gold project.

"I am very proud of what we did there in Serbia. When we focus on this amazing project, we always abide by the laws and regulations of Serbia. " He said.

"now we just want to take care of our people in this country," he said, adding that he had nothing more to say about Serbia.

Rio is reviewing the legal basis for the decision and may sue Serbia for trying to save the $2.4 billion project.

The company worked on the Serbian project last year because of the metals needed by global miners to transform green energy, including lithium, which is used to make batteries for electric cars.

In addition to boric acid for ceramics and batteries and sodium sulfate for detergents, the mine plans to produce enough lithium to power 1 million electric vehicles.

At full capacity, the mine is expected to produce 58000 tons of refined battery-grade lithium carbonate a year, making it the largest lithium mine in Europe.