KINGSTON, Jamaica (AFP) — Scientists present at the latest effort to hash out international rules for deep-sea mining say it's unclear if it's possible to restore damaged sea floor ecosystems — or how long it would take.

One of the last wild zones on the planet, the sea floor is a coveted frontier for companies and countries eager to access minerals that are in high demand for emerging technologies such as electric cars.

Particularly coveted are potato-sized nodules containing cobalt, nickel, copper and manganese, that are found in abundance on the seabed in the central Pacific Ocean.

Companies eager to vacuum up these polymetallic nodules say they can do it with minimal risk to the deep-sea environment.

But ocean defenders have battled against what they see as the advent of an industry that will threaten isolated ecosystems that are not yet well understood.

That threat was underscored by European scientists who presented findings this week on the sidelines of a meeting in Kingston, Jamaica of the International Seabed Authority, which is trying to finalize future rules for seabed mining.

"If we remove nodules from the seabed, we do not know what we lose, only that it's lost forever," was one of the conclusions of DEEP REST, a sea floor conservation research project.

The DEEP REST study cautioned against using seabed restoration "as a management action for impacted habitats."