It is the archetypal British dish, but our penchant for fish and chips may help support the trade in the endangered fin whale.

Unwitting consumers across the country are eating fish landed by an Icelandic firm with links to a company which resumed commercial fin whaling this summer – a practice banned by the International Whaling Commission in 1986 to conserve the species. The Commission’s authority is not recognised by Iceland.

Campaigners are calling on Warners Fish Merchants Ltd in Doncaster – which supplies 8 per cent of Britain’s fish and chip shops – to halt imports from the Icelandic fishing giant, HB Grandi, which has close links with the whaling company Hvalur.

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“British consumers care deeply about whales and dolphins and would be horrified to know that the fish and chips they are buying put more money into the pockets of the Icelandic whalers,” said Clare Perry, senior campaigner at the Environmental Investigation Agency.

She added: “Warners and other British companies should ensure there are absolutely no ties to whaling before importing fish from Icelandic companies or other companies from whaling countries like Norway, Japan and the Faroe Islands.”

Warners Fish Merchants describes itself as having “a strong relationship with HB Grandi” and is presumably aware that Kristjan Loftsson, owner of Hvalur, is chairman of its board. Warners does accept that HB Grandi and Hvalur have shared processing facilities. “HB Grandi has in the past leased one of its buildings to Hvalur for processing whale meat,” explained Gary Warner, managing director of Warners Fish Merchants. “[But] HB Grandi does not have any quota on whales, nor does it catch or process whales.”

Warners failed to provide The Independent with the names of the restaurants it supplies and HB Grandi was unable to respond to any requests.

The Environmental Investigation Agency believes up to 90 fin whales have been killed by Hvalur since hunting in Icelandic waters resumed after a two-year hiatus. The fin whale was heavily hunted during the 20th century and is classed as endangered by the International Union for Conservation of Nature.

In 1986 the International Whaling Commission issued a moratorium on commercial hunting of fin whale but Iceland and Japan – both members of the commission – continue to hunt the animals. Japan insists this is only for scientific purposes, even if most of the meat ends up on the market for consumption.

“Fin whales are endangered ... so there are very real conservation issues with the Icelandic hunt,” Ms Perry said. “They are the second-largest mammal on the planet and at that size it is impossible to kill them humanely.”

Hvalur failed to respond to The Independent’s inquiries, but in previous interviews with the media Kristjan Loftsson has claimed there is minimal suffering on the part of the whales, which are shot with explosive harpoons that detonate in their brains. Defending his enterprise, he said: “I think the UK’s position on whaling is out of a guilty conscience,” he said. “Between 1932 and 1966, UK-flagged vessels took 63,000 blue whales and over 105,000 fin whales – we are taking 150.”

He added: “We wouldn’t be whaling if it wasn’t sustainable – we have a stock of 20,000.”

Dog’s dinner: Where it goes

Iceland’s whalers are expected to hunt as many as 150 fin whales this summer, as unsuspecting holiday makers pay for whale-watching excursions elsewhere on the island.

Most of the whale meat is exported to Japan, where earlier this year the Environmental Investigation Agency discovered it was being used as an ingredient in dog food.