OSLO - A small leftwing environmentalist political party in Norway succeeded on Sunday in blocking plans to mine the sea bed at the bottom of the Arctic, by demanding the government scrap its first licensing round in return for support for the budget.

"We are stopping plans to open mining on the sea bed," Kirsti Bergstoe, leader of the SV party which is outside the governing coalition but supports the minority government, told reporters.

The government, which had planned to offer its first deep-sea mining exploration permits in the first half of 2025, said that although the plan was suspended, preparatory work would continue, including creating regulations and mapping the environmental impact.

"This will be a postponement," Prime Minister Jonas Gahr Stoere, from the Labour Party, told private broadcaster TV2.

Norway, whose vast hydrocarbon reserves made it one of the world's wealthiest countries, had taken a leading role in the global race to mine the ocean floor for metals that are in high demand as nations transition away from fossil fuels.

"This is a crucial win in the fight against deep sea mining. It should be the nail in the coffin for the destructive industry," Frode Pleym, head of Greenpeace Norway, told Reuters.

Oslo had plans to open large areas of its Arctic region next year for its inaugural sea bed licensing round, despite opposition from green campaigners and a coalition of 32 countries, including Germany, France, Canada and Brazil.

The agreement concluded on Sunday by SV and the government, consisting of Labour and the agrarian Centre Party, means that planned licensing round will not proceed.

Norwegians head to the polls in September and two opposition parties leading in opinion surveys, the Conservatives and the Progress Party, are in favour of deep-sea mining.

"If a new government attempts to reopen the licensing round we will fight relentlessly against it," said Greenpeace's Pleym.

Preliminary official resource estimates showed "substantial" accumulations of metals and minerals, ranging from copper to rare earth elements, the government said in 2023.

At least three Norwegian seabed mineral start-ups - Stavanger-based Loke, Oslo-based Green Minerals and Bergen-based Adepth, have previously said they planned to bid in the first licensing round.

The companies were not immediately available for comment.