SYDNEY - Global heavyweight Rio Tinto and China's Sinosteel have extended their Australian joint venture to supply 70 million tons of iron ore over the next five years, furthering one of the longest running partnerships in the Aussie-Sino trade relationship.

The extension, the second in the 29 years of the Channar joint venture that's provided for the production of 250 million tons of iron ore, will add a further 30 million tons. The remaining 40 million will come from a separate sales agreement in force until 2021.

The joint venture has been heralded as the cornerstone of the China-Australia economic relationship, given the current economic climate.

"In the 50-years that we have been exporting iron ore from the Pilbara, the Channar joint venture stands out as one of the most important deals not only for our business, but for Australia's economic ties with China," Rio Tinto's iron ore chief Andrew Harding said in a statement on Friday.

Sinosteel will pay a one-off $45 million fee as well as additional production royalties linked to the iron ore price, capped at $500 million to comply with UK listing regulations.