Global miner Rio Tinto says it has committed an additional $US1.3 billion ($A1.2 billion) to the development of the huge Simandou iron ore field project in Guinea.

“Rio Tinto is accelerating the development of the Simandou iron ore project in Guinea with the approval of a further $US211 million for continued studies and $US1.117 billion of funding for commitments for early works and procurement,” the mining giant said in an official statement on Tuesday.

“This funding willallow the project to move forward towards first shipment of ore by mid-2015.”

The announcement brings the total amount spent or committed to the project to $US3 billion, including $US700 million paid to the Guinean government to secure the right to mine in two sections of the huge deposit.

“This funding highlights Rio Tinto’s commitment to honouring the settlement agreement reached with the government of Guinea in April this year, and maintains the rapid build-up of in-country infrastructure in order to deliver first shipments of ore by mid-2015,” said Rio Tinto’s iron ore chief Sam Walsh.

Back in April, Rio Tinto settled a long-running dispute over Guinea’s huge Simandou iron ore field, with the West African nation agreeing to take a stake of up to 35 per cent.

The agreement ended a protracted impasse with Guinea over the Simandou project, which is a joint venture with China’s Chalco expected to produce vast quantities of high-grade ore.

Rio Tinto added on Tuesday that it was working towards securing regulatory approvals to allow it to enter into a $US1.35-billion deal to sell a 44.65 per cent stake in Simandou to Chalco.