(Reuters) -Rio Tinto has held talks with the Democratic Republic of Congo about developing one of the world's biggest hard rock lithium deposits, Bloomberg News reported on Friday, citing people familiar with the matter.

The discussions, which are in the preliminary stages, focus on Rio Tinto getting involved in transforming the Roche Dure resource into a lithium mine, the report added.

The world's largest iron-ore miner has been shifting its focus to critical minerals and battery metals like lithium, capitalizing on a price plunge caused by oversupply.

Rio Tinto declined to comment on the report when contacted by Reuters, while Congo's Ministry of Mines did not comment.

Rio Tinto CEO Jakob Stausholm told Reuters last year that a weak market had yielded an opportunity to pick up top quality assets at the right price, triggering its $6.7 billion buy of Arcadium Lithium.