Rio Tinto has almost doubled its half year net profit to $US3.3 billion due to higher iron ore and coal prices.

The mining giant said higher prices increased its underlying earnings by more than of $US2.7 billion in the six months to June, with iron ore prices up 42 per cent from a year earlier, and coking coal more than three times higher.

Rio’s underlying earnings, which excludes impairments and exchange losses, more than doubled to $US3.9 billion, which is slightly weaker than market expections.

Chief executive Jean-Sebastien Jacques said Rio would deliver cash returns of $US3 billion to its shareholders through an increased dividend and additional $US1 billion buyback of its London-listed shares.

The interim dividend of $US1.10 is up from 45 US cents a year earlier.

Prices for iron ore, Rio’s primary earner, peaked at nearly $US95 a tonne in February, but have moderated since amid concerns of oversupply and a slowing Chinese economy.

Iron ore currently trades around $US73 a tonne.

The company’s underlying earnings from iron ore increased 87 per cent to $US3.3 billion, while earnings from its energy division increased almost eight-fold to $US652 million.

Rio Tinto expects capital expenditure to remain at around $US5 billion in 2017 and around $US5.5 billion in both 2018 and 2019.

Rio Tinto profit soars as prices rise

• Half year net profit up 93pct to $US3.3b
• Revenue up 25pct to $US19.3b
• Interim dividend up 65 US cents to $US1.10 per share