Brand Finance looks at marketing investment, stakeholder equity and the impact of those on a company's performance to produce its brand strength rating.

Despite falling 1.1% year on year, Rio's score of 71.8 beat BHP's 71 after the latter registered a 2.5% drop versus 2018. Vale came third with a score of 66.2, down 5.2%.

"As with the majority of brands in the ranking, Rio Tinto has dropped in brand strength this year as the sector faces increased scrutiny and intolerance in the face of climate change and global heating challenges." Brand Finance said in its annual mining brand report.

"Despite the brand pledging $1 billion over the next five years to reduce its carbon footprint and reach net zero emissions by 2050, Rio Tinto has been unable to avoid the heat from activists and green groups.

"How the brand responds to this criticism will no doubt impact the brand's reputation and stakeholder engagement, and thus its brand strength in the coming year," said the consultancy.

Though Rio triumphed from a brand strength perspective, it continues to languish five spots behind BHP on brand value - the primary metric used by Brand Finance to assess brand performance.

BHP retained its title in 2019 as the world's most valuable brand, with a brand value of US$5.8 billion.

Brand Finance approaches valuation by estimating the likely future revenues attributable to a brand by calculating a royalty rate a company would charge for its use.

BHP's brand value was down 3% year on year after a tough 12 months during which the company negotiated a US$5 billion lawsuit following the Samarco dam disaster in Brazil and battled Australian bushfires which severely hampered coal output.

Other notable movers in brand value were Citic Pacific Mining, which recorded a 25% increase in brand value to US$2.7 billion.

"CITIC Pacific Mining has been exposed to various obstacles, from the slowing Chinese economy to global geopolitical turmoil. However, the brand has taken successful steps to protect itself from this uncertainty, through consistent plant acquisitions and its focus on developing the fundamentals of the business, ensuring the brand retains a competitive position in the long-term," said Brand Finance.