Officials in Norway are investigating after a beluga whale was found wearing a tight harness, prompting speculation the animal may have escaped from a Russian military facility.
The Norwegian Directorate of Fisheries said "Equipment St Petersburg" was written on the harness strap, which features a mount for an action camera.
They also posted a series of images on social media of the incident which took place in the waters around West Finnmark.
Spokesman Joergen Ree Wiig said fishermen in Arctic Norway last week reported the tame white cetacean with a tight harness swimming around.
Hvithvalen utenfor Finnmarkskysten som hadde stramme stropper festet rundt kroppen er fri. Mannskap fra Fiskeridirektoratets sjøtjeneste er trent til å frigjøre hvaler fra tauverk og fiskeredskaper og sammen med den lokale fiskeren Joar Hesten greide de i går å frigjøre hvalen. pic.twitter.com/T00vb37xV6— Fiskeridirektoratet (@fiskeridir) April 27, 2019
On Friday, a fisherman jumped into the frigid water to remove the harness.
Mr Wiig said "people in Norway's military have shown great interest" in the harness.
Norwegian media reported that the mammal was found attempting to pull at ropes on the side of boats, with the Aftenposten newspaper claiming that the Russian military is believed to have trained sea mammals.
Russia is one of a number of countries known to have trained dolphins for military purposes.
Audun Rikardsen, a professor at the Department of Arctic and Marine Biology at the Arctic University of Norway in Tromsoe, said he believes "it is most likely that Russian Navy in Murmansk" is involved.
Russia has major military facilities in and around Murmansk on the Kola Peninsula, in the far north-west of Russia.
Mr Rikardsen said he had checked with scholars in Russia and Norway and said they have not reported any programme or experiments using beluga whales.
"This is a tame animal that is used to get food served so that is why it has made contacts with the fishermen," he said.
"The question is now whether it can survive by finding food by itself.
"We have seen cases where other whales that have been in Russian captivity doing fine."