(Adds details of pre-feasibility study and background from...

(Adds details of pre-feasibility study and background from paragraphs 2 to 7)

Dec 5 (Reuters) - Rio Tinto (RIO) , the world's largest iron-ore producer, has approved $77 million for the development of the Rhodes Ridge project in Western Australia, the company said on Tuesday.

The pre-feasibility study (PFS) for the project is expected to be completed by the end of 2025 with the first ore expected to be produced by the end of this decade, the company added.

The development would add 40 million tonnes a year to Rio's Western Australian iron ore operations.

Rio expects to produce 320-335 million tonnes of iron ore from Western Australia this year.

"The size and quality of the resource base at Rhodes Ridge has the potential to underpin our iron ore business in the Pilbara for decades to come," Rio Tinto Iron Ore Chief Executive Simon Trott said.

"Longer term, the resource could support a world-class mining hub with a potential capacity of more than 100 million tonnes of high-quality iron ore a year", he added.

Rio is planning to spend more than A$400 million ($264.68 million) on exploration for the project over five years from 2024 to 2028 as part of the ongoing study phases.

($1 = 1.5113 Australian dollars)