About one in seven fish sold in shops, restaurants or fish and chip shops may not be what they say on packs or menus, according to trading standards checks.

Figures supplied by councils to the UK Food Standards Agency indicate that 41 of 303 checks on packaged frozen or chilled fish and in catering businesses in 2011 did not meet labelling requirements.

In 27 cases the fish described as cod was another species, such as haddock, whiting or pollock. Other types of fish were also incorrectly described among other breaches of labelling rules. said the agency.

The UK fishing industry has demanded tougher action to ensure consumers are not misled over the type of fish they are eating amid mounting evidence of mislabelling of fish internationally and as Europe reels from the horsemeat in beef scandal.

The FSA has previously reported checks by trading standards officials in 2008 that suggested one in 10 fish in 380 samples from catering establishmentswere not those described on menus.

Checks in 1994, before the agency existed, suggested 8% of fish in catering outlets were mislabelled.

Information about the latest figures came after Stefano Mariani, of Salford University, told the BBC: "Consumers should be able to go to a shop and know they are eating what they paid for."

Mariani previously led a study at University College, Dublin, which found that 7% of products labelled as cod in the UK and 28% in Ireland contained substitutes, such as pollock and whiting. It involved DNA testing on 226 products in 131 supermarkets, fishmongers and takeaways in Ireland and 95 in the UK.

He is now involved in a European study concentrating on the UK, Ireland, Portugal, Spain, France, and Germany but also looking at the Netherlands, Belgium, Sweden, Norway, Iceland and Estonia.

"A lot of the fish used are perfectly edible and from possibly more sustainable stocks", Mariani said. "The problem is they should be sold for what they are."

Oceana, an organisation which campaigns to protect seas and oceans, has also recently found widespread mislabelling of fish in the US.

Paul Williams, chief executive of Seafish, the national industry body, said deliberately mislabelling seafood was "unacceptable and damaging to an industry which prides itself on the quality and sustainability of its products". Anyone found to be deliberately misleading consumers was dealt with immediately by trading standards authorities.

Barrie Deas, who heads the National Federation of Fishing Organisations was concerned that "cheap, low quality imports of species like tilapia, pangasius and Alaskan pollock are being substituted for fish caught in our waters and mislabelled as more familiar species."

Improved DNA testing should make checks easier and help prevent fishermen and consumers being cheated, said Deas. "We have the means, just get on and do it."

Those found guilty of breaking labelling rules face fines of up to £20,000 or up to two years imprisonment. Those convicted of fraud can be jailed for up to 10 years or face unlimited fines. The Trading Standards Institute says local authority budgets are tight and it has no national figures on labelling infringements.