KABUL: Afghanistan has opened bids on copper and gold deposits in four areas of the country that together are roughly half the size of the Grand Canyon.

Afghanistan hopes its budding mining industry will generate billions in revenue to help rebuild the nation after 30 years of war.

The Afghan Ministry of Mines on Tuesday opened bids for multiple contracts to unearth copper and gold hidden beneath 846 square miles (2,191 square kilometers) in Badakhshan, Ghazni and Herat provinces and a fourth area that spans both Balkh and Sar-e-Pul provinces.

The US Defence Department put a $1 trillion price tag on Afghanistan's deposits of iron ore, copper, gold and other minerals.

The Afghan ministry says other reports estimate the nation's mineral wealth at $3 trillion or more.