Shares in Norwegian sea bed mining start-up Green Minerals fell by 40% on Monday after the government scrapped a first licensing round for deep-sea mining in return for support for its annual budget.

A small leftwing environmentalist political party in Norway succeeded on Sunday in blocking plans to mine the Arctic sea bed by supporting the minority coalition's budget on the condition that it stopped the licensing round.

Green Minerals's shares were trading at 3.88 crowns ($0.3501) at 10:30 GMT, despite the company saying it expected the halt to be temporary.

"The company does not change its estimated timeline for first ore, still expected to take place in the very end of the 2020's," Green Minerals said in a statement.

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

Norwegians also 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.

Without referring to next year's election, Green Minerals said that after a 12-month delay it expected "a slightly accelerated timeline" which would allow the first round of licenses to be awarded "sufficiently early in 2026" to uphold its timeline for first exploration in the same year.

Norway, where vast hydrocarbon reserves have made it one of the world's wealthiest countries, has been a leader in the global race to mine the ocean floor for metals that are in high demand as nations transition away from fossil fuels.

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

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