Image caption Vale of Glamorgan council insists all scores must be clearly visible

Some of Wales' least hygienic takeaways and pubs are flouting the law by failing to display their poor food hygiene ratings, an investigation by BBC Wales' X-Ray programme has revealed.

When undercover X-Ray researchers visited zero-rated food premises in the Vale of Glamorgan all but one failed to disclose their score.

Wales is the only part of the UK where customers have a legal right to know the food hygiene rating of their local café or takeaway.

Scores range from a "very good" five to zero, meaning "in need of urgent improvement".

Stickers featuring the score must be prominently displayed and staff must tell customers their score if they ask. There is a £200 fixed penalty notice for failing to do this.

'Lost sticker'

Whilst food premises which have a high score display their scores prominently - in some cases on giant banner adverts - X-Ray has found that some of the least hygienic break the law and lie about their ratings.

The programme targeted the Vale of Glamorgan which had the highest proportion of zero-rated food outlets in Wales, according to the Food Standards Agency's website.

An X-Ray researcher visited all of those in the county which should have been displaying a zero rating.

No hygiene scores were seen at any of the premises - and when undercover researchers asked, only one restaurant - the Sully Inn, near Barry - was honest about the score.

In Barry, Pizza Knight and Mariano's Pizzeria claimed not to have a score, the Far East takeaway falsely claimed theirs was under review and Romeo Pizza said they had a "good" rating of four.

Image caption Rob Wilkins said sanctions should be imposed on those who do not comply

Rob Wilkins from the Food Standards Agency, which oversees the food hygiene rating scheme, was concerned by the findings.

"It's clearly not what the legislation was introduced for. Customers can expect to see stickers in windows and they can expect an honest answer from food business operators," he said.

"For those businesses that are not prepared to partake in it there are sanctions and they should be applied."

At least 45 businesses in Wales have already received £200 fixed penalty notices for failing to display their hygiene ratings and there have been several prosecutions for repeated breaches of the law.

Enforcement action

When asked why they failed to display their zero sticker, The Sully Inn said staff removed it when its door was re-glazed, but it has now been replaced and the rating has increased to '1'.

The Far East takeaway did not comment, but is now showing its score. Romeo Pizza claimed to have lost its sticker and both Pizza Knight and Mariano's Pizzeria blamed drunk customers for stealing theirs.

Mariano's Pizzeria insists a sticker was on display. But on the three occasions X-Ray researchers looked for it they did not see it, perhaps because it was high on a window and partially obscured by shutters.

Vale of Glamorgan council insists all scores must be clearly visible. It is now investigating all the businesses and is considering enforcement action against them.

Supporters of the scheme say that - despite X-Ray's finding - the scheme has led to a big improvement in the hygiene standards of food premises since it was introduced in 2013.

More than half of the country's 25,000 food premises now have a top rating of 5.

X-Ray is on BBC One Wales at 19:30 GMT on Monday, 9 February.