Rio Tinto, which is one of Australia's biggest corporate tax and royalties payers after handing over $9.5 billion in 2025, revealed on Tuesday it sold two per cent more iron ore in the March quarter than in the same period the year before.
The result was driven by its Pilbara operation in Western Australia, which in turn delivered a 13 per cent boost in production - its second-highest first-quarter result since 2018 - to 78.8 metric tonnes.
Rio boss Simon Trott said the group was monitoring the situation in the Middle East, after the US-led attack on Iran on February 28 that has since disrupted shipping lanes in the Strait of Hormuz and sent oil prices soaring.
"The unmatchable mix and scale of our portfolio has ensured growth and supply chain resilience," the chief executive said in a statement.
However, the outlook for the second half of its 2026 calendar year is unclear.
So far, the supply impact on its operations has been limited, while the jump in commodity prices has been in its favour.
"We continue to monitor the evolving global impact closely and have contingency plans in place," Rio said.
"However, we have relatively limited visibility of how the ongoing conflict will affect supply chains in'' the second half, it said.
Rio consumes about 1.6 billion litres of diesel fuel - roughly equal to 650 Olympic-sized swimming pools - each year, with most of that being used in the Pilbara.
"Despite higher diesel prices steepening the cost curve, our cost position is resilient, underpinned by scale and global supply-chain leverage," it added.
The miner, which has been looking at ways to bulk up its copper portfolio amid a global scramble for the valuable base metal, also reported that copper production rose nine per cent in the March quarter as its Oyu Tolgoi mine in Mongolia continues to ramp up.
In February, Rio walked away from a proposed merger with copper and commodities rival Glencore, which could have made it the world's largest mining company with a market value of close to $300 billion.
It was the fourth time a plan to combine the companies had collapsed, after the idea was floated in 2008.
Rio said the pair failed to agree on a price that delivered shareholder value, while Glencore said handing over control of the combined entity to Rio was a deal breaker.
Rio shares inched 0.4 per cent higher to $173.14 in morning trade.
