Nomad Foods, the owner of the Birds Eye, Iglo and Findus frozen food brands, said it is finding ways to source fish outside of Russia, including other species such as hake and farmed whitefish as it seeks to reduce its a strong dependence on Russian whitefish.

Nomad CEO Stefan Descheemaeker said moves to diversify away from Russian fish are happening but warned that the process is not a quick one.

"It's not like you switch off and switch on the light," he said.