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Food ordering app Just Eat is to remove all restaurants with a hygiene rating of zero from their platform.

Any new outlet attempting to join Just Eat will also have to be rated at least "generally satisfactory" - a three on the five point scale - for hygiene.

It comes after a BBC investigation found half of outlets rated zero by the Food Standards Agency in Manchester, Bristol and London appeared on the app.

Just Eat said restaurants rated zero would be removed by 1 May.

In England, Wales, and Northern Ireland a hygiene rating of zero means "urgent improvement is required".

In October, the BBC found one takeaway with a zero rating, featured on Just Eat, had mouse droppings on washing up gloves and dead mice in a pool of grease in the kitchen.

Image copyright Waltham Forest Council Image caption Environmental Health took this picture of dead mice at a takeaway in Walthamstow, east London which features on Just Eat

Just Eat says it will be investing £1m to raise food hygiene and safety standards, and will help any restaurant on its platform with a rating of zero, one or two to improve.

It will fund a one-to-one visit from an expert food safety practitioner, help to draw up an action plan, and offer guidance on how to request a re-inspection.

The company says outlets that fail to make changes and are still rated zero by 1 May will be kicked off.

"We know that running a small, independent business is not without its challenges, and food hygiene and safety is a vital area that restaurants need to get right," said managing director Graham Corfield.

The company added that "the vast majority" of takeaway restaurants have a good hygiene rating score.

How do food hygiene ratings work?

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Local authorities are responsible for inspecting restaurants and takeaways.

In England, Wales and Northern Ireland outlets are given a rating ranging from zero, for "in need of urgent improvement", to five, for "food hygiene is very good".

In Scotland there are just three ratings - Pass, Improvement Required and Exempt Premises (which are given to premises such as newsagents or chemists that are checked but are not predominantly food businesses).

Just Eat will also offer help to those who need improvement in Scotland.

Restaurants in Wales and Northern Ireland must display their rating prominently.

In England, many outlets choose to do so, particularly if it shows a high score for hygiene, but it is not mandatory.

Just Eat announced in December that it would start to include the official FSA food hygiene rating of each restaurant more prominently on its website and app - something it is now doing in Northern Ireland.

Until it's rolled out across the UK though, most users must leave the app and look up the rating on the FSA website.

Media playback is unsupported on your device Media caption An investigation by the BBC last year found Just Eat were listing outlets rated zero by the FSA

Heather Hancock, chairman of the FSA, welcomed Just Eat's investment.

She said: "The company influences thousands of food businesses and reaches millions of customers.

"Quite rightly, Just Eat is making clear that food safety and hygiene must be a top priority for all their partner businesses."