Rio Tinto plans to dispute the amended tax assessments it recently received from the Australian Commissioner of Taxation, or ATO, billing the miner A$447 million in additional tax and interest for the calendar years 2010 to 2013.

According to an April 5 company statement, the ATO confirmed that the amended assessments do not relate to any tax avoidance issue. The new tax bill is from the pricing of certain transactions between Rio Tinto entities based in Australia and the group's commercial center in Singapore.

The amount comes on top of the A$25.5 billion of taxes and royalties the mining giant paid in Australia during the same four-year period, but Rio Tinto said it will pay 50% of the A$447 million tax bill within the month.

Rio Tinto also plans to seek double taxation relief, in accordance with the Australia-Singapore double tax treaty, and assured that its pricing is in accordance with internationally recognized guidelines and Australian domestic laws.