Anti-corruption coalition Transparency International placed the two companies just behind Norwegian oil and gas producer Statoil in its report, Transparency in Global Reporting.
The three were the only companies to score in the top 10 in each of the three dimensions of transparency.
Companies were scored from 0-10 based on their disclosure of various sorts of business information important for investors and the general public including where they paid their taxes, their corporate structures and what they were doing to prevent corruption.
A score of 10 was most transparent and Rio and BHP each scored 7.2.
Transparency International praised the two companies for their reports on anti-corruption programs and their disclosure of organisational transparency and what taxes they each pay on a country-by-country basis.
Rio paid $US10.2 billion ($A10 billion) in taxes last year, which was 40% more than 2010, including $6.7 billion in Australia alone.
“We have chosen to disclose these details voluntarily because we believe this level of transparency helps us to retain our licence to operate, promotes government accountability and plays a role in combating corruption,” Rio chief financial officer Guy Elliot said earlier this year.
BHP paid $5.3 billion in tax for the six months to December 2011.
Transparency International said transparency was crucial in a time when countries were struggling to rebuild battering economies.
“Ultimately, companies with a good track record of reporting on their anti-corruption programmes and global activities are more likely to be part of the solution than the problem,” the report said.
It echoes comments made by Rio chairman Jan du Plessis in London last week in a speech about regaining corporate trust.
“We now live in a world where society is continually upping its expectations of companies – in particular those that operate in the multi-national arena,” he said.
“If we show trust at the top and move the debate into something more dignified than that which we have seen in recent times, we can begin the long, slow process of rebuilding trust with those whom we seek to serve.
“There is a long haul ahead, but we must start the work of rebuilding trust today, because without trust there can be no confidence and without confidence we will struggle to build the road to a genuine, sustainable economic recovery.”
Steelmaker ArcelorMittal came in just behind BHP and Rio in fourth place with a score of 6.9, while the world’s largest iron ore producer Vale was well down the list with a score of just 4.7.
Of the 105 companies covered – which had a combined market capitalisation of more than $US11 trillion – BHP and Rio were among a handful which provided feedback during the data review process, which Transparency International said improved the standard and quality of the report.
Rio was also a member of Transparency International’s Business Principles Steering Committee.
While resources companies were the best performers, financial companies were the worst, with 24 banks receiving an average score of 4.2 and the Bank of China receiving a score of just 1.1.
