Tons of plastic packaging destined for recycling from popular British supermarkets like Sainsbury's and French frozen food retailer Picard is instead ending up being dumped illegally in Turkey as the country has become the top destination for European waste.

Recycling firms in Turkey defend the rise in imports, arguing the waste plastic is needed for the growing industry which allows the reuse of material that otherwise clogs landfills for decades.

But the environmental consequences are increasingly hard to ignore, with illegally dumped plastics visible around the growing number of sites in southern Turkey where European plastics are meant to be processed.

There are at least 10 known sites in southern Turkey where European plastics have been dumped illegally.

"European citizens need to know this: the last stop for their waste that they carefully separate into different boxes is not a recycling facility," said Sedat Gündoğdu, a professor at Çukurova University in Adana. "It's here where there are mountains of waste."

While it is unclear just how much of the imported waste plastic meant to be recycled is ending up in illegal dumps, as long as recycling is expensive it remains a possibility.

As Western Europe pays for the waste to be taken away, there is a financial temptation for Turkish firms that import it to dump it rather than pay to recycle it.

Interpol warned in August about the rising involvement of criminal organizations in the global illegal plastic waste trade.

And activists have warned about the environmental problems caused by illegal dumping and burning of plastic waste.

Despite its green aspirations, the EU still recycles less than a third of its plastic waste, burning or burying the rest. It only recycles half that itself, sending the remainder abroad.

Turkey became Europe's go-to destination for plastic waste after China began to close its doors to foreign waste from January 2018.

Monthly imports of plastic waste from Europe leapt by more than tenfold from 2016 to 2019, according to Eurostat data, with Turkey taking in nearly a quarter of what the EU exported last year.

In September, Turkey's Ministry of Environment and Urbanism instructed recycling companies to import no more than 50% of their needs and to source the other half domestically.

But not all plastics imported from Europe end up being dumped along roadsides, as in the province of Gaziantep, where an empty Sainsbury's bottle of olive oil began its journey to become thread.

Plastic bottles imported from Europe and the United States are cleaned, ground into flakes and melted down to become fiber which is then transformed into thread for use in clothes.

GAMA Recycle exports 1,500 tons of it every month to 30 countries, including Spain.

However, Gündoğdu said there is a false idea among the public that plastic is suitable for use as it is being recycled when a drastic reduction in their use is needed.

Environmentalists now worry about a surge in the use of plastic because of the coronavirus pandemic as people don masks, gloves and other personal protective equipment.

Some of the illegally dumped waste ends up in rivers that empty into the Mediterranean Sea, with the plastic washing up on Turkish beaches, putting the tourism industry at risk.

"We come across single-use plastics the most in the seas," said Greenpeace Mediterranean's plastics project director Nihan Temiz Atas, who called for a ban on their use.