LA PAZ - Bolivian President Luis Arce said on Thursday he would be willing to jointly design a lithium policy with other Latin American countries to benefit their economies, echoing a similar proposal from Mexico's President.

Bolivia has an estimated 21-million tonnes of untapped lithium resources, the most worldwide, in an area of sprawling salt flats delineating the so-called "lithium triangle" that includes northern Chile and Argentina.

"We must be united in the market, in a sovereign manner, with prices that benefit our economies, and one of the ways, already proposed by (Mexico's) President Andres Manuel Lopez Obrador, is to think of a kind of lithium OPEC," Arce said in a speech in La Paz.

The objective is to position Bolivia, Chile, Argentina and Peru "as potential promoters of new forms of energy storage that will make it possible to overcome the use of fossil fuels," said Arce.

Demand for lithium, used in rechargeable batteries for cars and electronics, pushed prices for battery-grade metal to around $85,000 per tonne at the end of last year.

Arce expressed concern about foreign meddling in the lithium business, in particular from the United States.

"We don't want our lithium to be in the Southern Command's crosshairs, nor do we want it to be a reason for destabilizing democratically elected governments or foreign harassment," he said.

On March 8, U.S. Southern Command General Laura Richardson told a Congressional hearing that China was exploiting the region's resources and its actions could hamper conditions for private investment.

"They don't invest, they extract ... the ground game that they have with lithium is very advanced and very aggressive," Richardson said.

The world's largest lithium producer is US miner Albermarle, which operates in northern Chile. US firms such as Livent Corp are also set to supply Argentine lithium to BMW.

The second-largest producer, Chile's SQM, was about 24% held by China's Tianqi Lithium at the end of 2021. Chinese battery giant CATL and Ganfeng Lithium have also been growing their Latin American footprint.