A beluga whale harassing Norwegian fishing boats in the Arctic Circle last week shows signs of being a Russian navy asset, marine scientists say.

The white whale had been biting fishing nets and headbutting boats off the island of Ingoya.

Scientists used cod fillets to lure it and cut off the harness, which said "Equipment St. Petersburg."

Scientists from the Institute of Marine Research in Norway and the Arctic University of Norway told news outlets that the whale was likely part of the Russian navy.

Militaries in Russia, Ukraine, and the US have used marine animals before.

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Scientists in Norway say that a harness-wearing beluga whale found harassing fishers off the northern coast of Norway last week is most likely a tool of the Russian military.

Experts from Norway's Institute of Marine Research intervened on Thursday after fishers told them that the whale had been headbutting their boats and gnawing nets off the island of Ingoya in the Arctic Circle.

The institute's Martin Biuw told the Norwegian broadcaster NRK: "If this whale comes from Russia — and there is great reason to believe it — then it is not Russian scientists but rather the navy that has done this."

Biuw said that civilian scientists would not attach harnesses to marine animals.

Images from the Norwegian broadcaster NRK showing the whale strapped with a harness. NRK

Experts from the institute, along with Norwegian government officials, lured the whale with cod fillets before taking off the harness, which images show has the English words "Equipment St. Petersburg" on it.

Scientists said it had an attachment that could fit a GoPro camera and was likely used to hold surveillance equipment like cameras or other marine sensors.

Scientists used cod fillets to lure the whale and cut off the harness. NRK

"We were going to put out nets when we saw a whale swimming between the boats," Joar Hesten, the fisher who reported the whale, told NRK.

"It came over to us, and as it approached, we saw that it had some sort of harness on it."

The clasp on the harness said "Equipment St. Petersburg." VG

Audun Rikardsen, from the Arctic University of Norway, told NRK: "We know that in Russia they have had domestic whales in captivity and also that some of these have apparently been released. Then they often seek out boats."

Rikardsen told the Norwegian newspaper VG that his Russian marine colleagues "tell me that it is most likely is the Russian navy in Murmansk," near Ingoya.

The location where scientists found the whale. Google Maps

Hesten told VG that the whale was very tame, seemed as if it wanted help, and showed clear signs that it had been trained by humans.

Read more: A Russian defense ministry report claims its elite soldiers can crash computers with their minds and read documents inside a safe after mastering telepathy from dolphins

Naval forces from the US, Russia, and Ukraine have used marine life, particularly dolphins, as assets.

The US has used dolphins to locate underwater mines and submarines since the 1960s. The US Navy's Marine Mammal Program in San Diego houses about 75 dolphins and 50 sea lions.

The whale swam off after the harness was removed. NRK

In Russia, dolphins are also trained to find underwater mines.

In 2016, Russia's navy bought five bottlenose dolphins for about $25,000, and in June 2017, Zvezda, a TV channel owned by Russia's defense ministry, said that whales, seals, and dolphins were being trained for military operations.

Russia took control of the Ukrainian military's "combat dolphin program" after it annexed Crimea in 2014, the state-owned news outlet RIA Novosti said. RIA Novosti claimed in 2012 that the Ukrainian dolphins were also being trained to kill enemy divers with knives and pistols attached to their heads.