OSLO - Norway's minority government should withdraw its proposal to open a vast Arctic offshore area to deep sea mining and call at least a ten-year moratorium on the activity, its key backer in parliament, said.

Norway could become the first nation to make deep sea mining happen on a commercial scale if the country's parliament approves a plan to open ocean an area larger than the United Kingdom to the new industry. The mining could provide a source for such metals as copper and rare earth elements for the transition away from fossil fuels.

The Labour-led government, which also includes the Centre Party, relies on a smaller leftwing party, the Socialist Left (SV), for support to pass its budget and other key policies in parliament.

"We will not vote for the proposal that the government has put forward. We think that it should be sent back to the government," Lars Haltbrekken, SV's spokesman on energy and environment, told Reuters.

"We would like to have a moratorium for at least ten years so that we can find out more (about the environmental consequences) before we start digging for minerals on the seabed," he added.

Haltbrekken said SV was still discussing a list of its demands for the upcoming fiscal budget, to be presented on October 6.

He did not say whether SV would make support for the government's budget conditional on the issue.

The government could still win the approval with support from the main opposition Conservative party, which initiated the opening process in 2020, as well as the right-wing Progress Party.

Still, Haltbrekken said deep sea mining was "high on our agenda" and "an important issue for us".

In 2021, SV blocked the government's plans to conduct oil and gas exploration licensing round in frontier areas.

Parliament is set to discuss the government's bill this autumn, although a specific date for debates has yet to be set.