BHP Billiton, the world's largest mining companyThe group announced on Thursday that it had worked with Tesla, a US electric car manufacturer.To reach an agreement on the supply of nickel.

Under the agreement, Western Nickel, a subsidiary of BHP Billiton in Western Australia, will supply Tesla with the metal. BHP Billiton did not provide further details, saying only that the two companies would work together to make the battery supply chain more sustainable.

Tesla CEO Musk has repeatedly expressed concern about the future supply of nickel. As more and more of the world turns to electric cars, demand for nickel is bound to soar, and Mr Musk has asked miners to produce more nickel.

Prior to that, Tesla had reached a series of agreements with mining companies on the commodities he needed to make batteries, including GlencoreThe cobalt agreement and a nickel joint venture in New Caledonia (New Caledonia).