Authorities in Norway have announced the discovery of huge reserves of metals and minerals, ranging from copper to rare earth elements, on the seabed of the country's extended continental shelf, CNN reports.

These resources are in high demand because they play a significant role in the transition to a greener economy.

Norway, a major oil and gas exporter, is considering opening its offshore areas to deep-water mining, which requires parliamentary approval and has environmentalists worried.

A resource assessment covering remote areas of the Norwegian and Greenland Seas found that polymetallic sulfides accumulated 38 million tons of copper, nearly twice the annual global production, and 45 million tons of zinc.

The sulfides occur along the mid-ocean ridge, where magma from the Earth's mantle reaches the seafloor, at a depth of about 3,000 meters.

About 24 million tons of magnesium and 3.1 million tons of cobalt are estimated to be in manganese crusts that have grown on bedrock over millions of years, as well as 1.7 million tons of cerium, a rare-earth element used in alloys.

By some estimates, the manganese crusts also contain other rare earth metals such as neodymium, yttrium and dysprosium.

Environmental groups have called on Norway to delay seafloor mineral exploration until more research can be done to understand the organisms living on the seafloor and the impact of mining on them.

The UN-linked International Seabed Authority, which oversees the deep-sea mining sector, is expected to announce rules for the fledgling industry in July. Many scientists warn that deep-sea mining could have enormous and irreversible consequences for the fragile ecosystem.