Thousands of food businesses across the country are failing to meet hygiene standards as overstretched local authorities struggle to carry out their inspection duties, new research has revealed.

Birmingham City Council and Hyndburn Borough Council were ranked as the worst areas in the UK for food hygiene enforcement for the second year running by consumer group Which?.

In Birmingham, 43 per cent of high and medium-risk food businesses didn’t meet compliance standards while 16 per cent of the 8,000 businesses in the sector are yet to be rated by the council.

Hyndburn in Lancashire was the second worst area in the UK for food hygiene in 2016-17, analysis of data collected by the Food Standards Agency found.

Almost all businesses in the borough had been rated for risk but just two in five of medium and high-risk food companies met food hygiene standards, compared with 98 per cent in Harrogate, which is about an hour away in North Yorkshire.

Erewash Borough Council in Derbyshire was rated the best out of 390 local authorities for the second year running. The borough carried out planned interventions on all failing premises while 97 per cent of its medium and high-risk establishments are compliant with hygiene standards.

Basingstoke and Deane Borough Council, both in Hampshire, were close behind with 96 per cent of medium and high-risk premises meeting food compliance standards and 99 per cent of food businesses inspected and rated for risk.

Three Rivers District Council, in Hertfordshire, saw the biggest improvement from the previous year. It jumped into the top 100 after being ranked among the worst 25 per cent of areas in 2015-16.

Which? analysed and ranked 390 local authorities across the UK using the following criteria: percentage of high and medium-risk food businesses compliant with food hygiene standards; percentage of food premises opened but not visited or rated for risk; and interventions required that have been carried out.

The consumer group warned that Brexit could further stretch local authorities’ food safety inspectors as the UK will need to step up checks on imports and potentially look to negotiate trade deals with countries with lower food standards.

Alex Neill, a managing director at Which?, said: “When it comes to food, British consumers expect the very best standards for themselves and their families.

“But our enforcement regime is under huge strain, just as Brexit threatens to add to the responsibilities of struggling local authorities.