AngloGold Ashanti will explore the seabed for gold as mining companies seek alternatives to replace increasingly scarce reserves.

AngloGold has formed a marine exploration company with diamond producer De Beers and will spend $40m in the next three to five years to explore undersea deposits, reports Bloomberg.

The new company has started operations off New Zealand’s coast and may move to sites off South America and Canada.

Bullion producers are trying to increase their reserves after gold rose more than fourfold during nine years of gains.

A dearth of high-grade deposits in traditional mining regions such as the US, Mexico and Australia is pushing miners into more difficult terrain, both physically and politically.