Pet food manufacturers must be more open about what they're putting in their products, according to TV vet Joe Inglis.

Speaking on BBC Radio 5 live this morning, he responded to concerns raised by University of Nottingham researchers that some pet food labelling does not always accurately relate to the ingredients in the product.

Several pet food brands contain beef, chicken and pork which is not listed on the ingredients, they said.

Mr Inglis, who is well known for his appearances on Vets in Practice, The One Show and This Morning, said: "The problem is transparency. We want to know what we're feeding them (pets). Pet owners need to know what's in there.

"The main ingredient is often not what you would expect."

The researchers found DNA from the three animals in 14 leading brands of dog and cat foods, despite the meats not being mentioned on the products' labels.

Two types of pet food which claimed to contain chicken, actually contained more pig or cow meat, and five samples "with beef" contained more pig DNA.

Kin-Chow Chang, of the University of Nottingham, said: "It may be a surprise to shoppers to discover that prominently described contents such as 'beef' on a tin could, within the guidelines, be a minor ingredient, have no bovine skeletal muscle (meat) and contain a majority of unidentified animal proteins."

Researchers say no regulations have been broken but that pet owners are not getting the products they expect and the current system could cause religious offence.

"Full disclosure of animal contents will allow more informed choices to be made on purchases which are particularly important for pets with food allergies, reduce the risk of product misinterpretation by shoppers, and avoid potential religious concerns," said Mr Chang.