Norway's Supreme Court on Monday ruled that two wind parks built in the country's west were harming reindeer herders from the Sami people by encroaching on their pastures.

It was not immediately clear what the consequences of the finding will be.

But lawyers for the herders say the 151 turbines completed on the Fosen peninsula in 2020 -- part of the biggest land-based wind park in Europe -- could be torn down.

"Their construction has been declared illegal, and it would be illegal to continue operating them," said Andreas Bronner, who represented a group of herders alleging harm from one of the two parks.

Ole Berthelsen, a spokesman for Norway's ministry for oil and energy, said that "the Supreme Court verdict creates a need to clarify the situation", adding it would "communicate later about what to do next".

The judges declared the licences issued by the ministry to build and operate the turbines void, saying they violated the International Covenant on Civil and Political Rights.

The UN text's Article 27 states that ethnic minorities "shall not be denied the right, in community with the other members of their group, to enjoy their own culture, to profess and practise their own religion, or to use their own language."

Reindeer herding is a traditional cultural practice of the Sami people
Reindeer herding is a traditional cultural practice of the Sami people AFP / Jonathan NACKSTRAND

Traditional Sami reindeer herding is a form of protected cultural practice, the Norwegian court found.

"Of course, this is a surprise to us," said Tom Kristian Larsen, head of Fosen Vind, which operates one of the wind farms.

"We based our action on definitive licences granted us by the authorities after a long and detailed process that heard from all parties," he added.

"Special importance was given to reindeer herding".

The company said it would now wait for the ministry's decision on next steps.

The Sami people number up to 100,000 people spread across Sweden, Finland, Norway and Russia.

Some of them make a living from raising semi-domesticated reindeer for their meat and hides.