The international seabed authority (ISA), a United Nations body, is drawing up regulations governing seabed mining in the high seas - areas outside any national jurisdiction. Until global rules are in place, sea bed mining is not allowed.

"With regard to possible future deep-sea mining, we highlight the unique chance to regulate a human activity before it is put into practice in order to prevent damage to the marine environment," the G7 ministers said in the final communique from their meeting.

They also said that an ability to demonstrate that the deep-sea environment would not be seriously harmed would be critical for them to consider consenting to any future mining permits in the ISA council.

Deep-sea mining involves sucking up potato-sized rocks rich in cobalt, nickel and other battery metals from the Pacific Ocean floor at depths of 4-6 km (2.5 to 3.7 miles).

Many scientists and environmentalists have called for a ban on deep-sea mining, saying it could cause lasting damage to little understood habitats. The World Wildlife Fund's call for a moratorium has been joined by companies including carmaker BMW and Alphabet Inc's Google.