Isa Opdahl had been out in a boat with friends at Hammerfest harbour in Norway on Monday when the handset plunged into the water.

The whale was filmed slowly emerging out of the ocean with the phone in its mouth after diving down to retrieve it. 

Ms Opdahl was then able to simply pluck the device from the whale's mouth.  

The footage has prompted speculation the whale is the same creature trained by the Russian military as a 'spy'.

Last week Norwegian fisherman discovered a beluga off the coast wearing a camera attached to a harness. 

Marine experts said the creature had been trained as a Russian operative that had escaped from a training facility.

Inspector Joergen Ree Wiig of the Norwegian Directorate of Fisheries, who was at the scene last week, said the harness was branded with 'equipment of St. Petersburg' and featured a mount for an action camera. 

Audun Rikardsen, an arctic and marine biology professor at the Arctic University of Norway, said it was 'most likely that the Russian Navy in Murmansk' was involved.