RIYADH - Saudi Arabia has revised upwards estimates for its untapped mineral resources including phosphate, gold and rare earths to $2.5-trillion, from a 2016 forecast of $1.3-trillion, its Mining Minister said.

Mining is a key part of Riyadh's efforts to build an economy that does not largely rely on oil, involving a shift towards tapping vast reserves of phosphate, gold, copper and bauxite.

Its Saudi Arabian Mining Company, known as Ma'aden and established in 1997, already produces some of these minerals.

"We believe today that our reserves' potential have now grown by 90%," Mining Minister Bandar Al-Khorayef told Reuters in an interview.

"This increase of $1.2-trillion is a combination of more of what we have, like phosphate, and new, like rare earths, and revaluation of (commodities) pricing," he added. A formal announcement will made on Wednesday during the Future Minerals Forum (FMF) mining gathering.

Al-Khorayef said that 10% of the increase in estimate comes from the addition of rare earths minerals, important for electric vehicles and high-tech products.

Saudi Arabia also plans to award over 30 mining exploration licences to international investors this year, he said.

He added that the kingdom will announce a new regulation that allows the mining ministry to offer larger exploration areas of more than 2 000 km for each license.

"One of the things we have heard from global players ... is that the size of the areas (awarded) is probably not as big as they want."

Riyadh has started awarding licences to international miners in 2022.

Al-Khorayef has also said previously that the kingdom plans to move beyond exploration and extraction to processing and manufacturing.

"Saudi Arabia could be a good place for processing of different minerals where we see minerals being mined in Africa being processed here."

As part of its push to diversify away from fossil fuels, Saudi Arabia has also established investment fund Manara Minerals, a joint venture between Ma'aden and the Public Investment Fund (PIF), to buy assets overseas.

Its first major foray abroad was a deal to become a 10% shareholder in Vale's $26-billion copper and nickel unit last July.

"Manara's ...management are looking around, finding different assets to buy or to partner with different countries."