LONDON, July 27 (Reuters) - Rio Tinto said on Tuesday it would invest $2.4 billion to develop its Jadar lithium project in Serbia, bringing forward an investment decision that was expected later in 2021, as demand for electric vehicle batteries is on the rise.

The Anglo-Australian miner expects construction to start in 2022 and last four years, subject to regulatory approvals.

Lithium is a vital ingredient in the batteries that power electric vehicles, and automakers, including BMW, Volkswagen and leader Tesla Inc, are increasingly looking to secure direct access to raw materials via partnerships with mining companies to avoid bottlenecks and keep plants at full capacity.

One in every nine new cars sold in Europe last year was an electric or plug-in hybrid vehicle.

Jadar is in the western Serbian city of Loznica and was discovered in 2004. It will include an underground mine and onsite processing facility that will produce battery-grade lithium carbonate, also used for storing renewable energy. It will also mine borates, used in solar panels and wind turbines.

Jadar is slated to position Rio as the largest lithium supplier in Europe for at least the next 15 years, the company said in a release ahead of its financial results on Wednesday.

"Serbia and Rio Tinto will be well-positioned to capture the opportunity offered by rising demand for lithium, driven by the global energy transition," said Chief Executive Officer Jakob Stausholm, adding that the company would supply enough lithium to power over 1 million electric vehicles per year.

(Reporting by Aby Jose Koilparambil, Clara Denina, Ivana Sekularac; Editing by Aditya Soni and Steve Orlofsky)