The five-year research is believed to be the most extensive yet on the possible consequences of modern commercial deep-sea mining machines on oceans already threatened by pollution and overfishing.

The industry plumbs previously untouched seabeds for commodities including nickel, cobalt and copper, which are used in everything from rechargeable batteries to military technology.

Deep-sea habitats also play a crucial role in the climate system.

Scientists from the UK's Natural History Museum (NHM), National Oceanography Centre, and Sweden's University of Gothenburg took baseline data on wildlife in the Clarion-Clipperton Zone (CCZ) -- an area of the Pacific Ocean that has been targeted for mining.

They found a 37-percent reduction in the number of tiny invertebrates such as worms and shellfish living within the sediment directly affected by the tracks of a mining machine.

- 'Critical evidence' -

NHM scientist Adrian Glover, the report's senior author, said the findings could inform policy discussions on deep-sea mining and help "set a new standard for environmental work in the region, regulated by the International Seabed Authority".

Nations are currently jousting through the authority over proposed rules on the industry.

A UN treaty on the high seas is set to become law in January 2026, aiming to protect vast expanses of the world's oceans.

No licences have been issued yet for commercial mining in high seas waters, but some countries have launched or are preparing to launch exploration in waters within their own exclusive economic zones.

The Cook Islands, in cooperation with China, awarded exploration licences to three companies in 2022.

The Metals Company in Canada wants to exploit international waters in the Pacific Ocean without the approval of the seabed authority, relying on a US law reinstated by President Donald Trump.

Norway on Wednesday, however, applied the brakes on issuing the first licences for its Arctic waters.

The licences were postponed for four years, which environmentalists hoped would end the plans.

Georgia Whitaker of Greenpeace International called for a global moratorium.

"We must not let this industry destroy unique marine life, not in the Clarion Clipperton Zone, the Arctic or anywhere," she said.