Global mining giant BHP Billiton on Tuesday said it will create a new independent company by spinning off some of its aluminium, coal, manganese, nickel and silver assets.

The world's biggest miner said this would allow it to focus exclusively on its core long-life operations -- iron ore, copper, petroleum, coal and potash -- while reducing costs and improving productivity.

The new entity will be listed in Australia with a secondary listing on the Johannesburg Stock Exchange with the demerger expected to be completed in the first half of the 2015 calendar year.

"For over a century, BHP Billiton has progressively reshaped its business to maintain its industry leadership," said BHP chairman Jac Nasser.

"We believe the proposed demerger, if implemented, will accelerate the simplification of the Group's portfolio, provide investors with choice and unlock value in both companies.

"Our shareholders will have the opportunity to vote on this proposal once the necessary approvals are in place."

The company said the new entity, to be named NewCo, would have assets in five countries.

It will be chaired by the long-serving David Crawford, a current BHP board member.

BHP first signalled in April it may sell some assets but did not say how this would be achieved with reports at the time saying the new company could be worth about Aus$20 billion ($18.5 billion).

"The assets that would form the new company are not of the same size as those in our major basins but many are among the largest and highest quality in their sectors," said BHP chief executive Andrew Mackenzie.

"We believe they will be more valuable in a purpose built, independent company than they would be in BHP Billiton."

AFP, photo by abc.net.au