Oct 23 (Reuters) - Australian gold explorer Calidus Resources said on Monday Chilean lithium miner SQM will buy a 30% stake in a lithium project in the Pilbara region from its joint venture partner Haoma Mining.

SQM will ultimately take its interest in Pirra Lithium Limited to 40% by injecting A$3 million ($1.90 million) to fund exploration, Calidus said.

Calidus, which owned Pirra equally with Haoma, will ultimately retain 40% ownership in the project by injecting A$2 million to fund exploration. ($1 = 1.5828 Australian dollars) (Reporting by Roshan Thomas in Bengaluru; Editing by Jacqueline Wong)