An area of the Sargasso Sea is more polluted with microplastic than a notorious high pollution part of the Pacific, researchers said yesterday.

The shock news came as environmental group Greenpeace revealed the results of a two- week survey of the Sargasso Sea, about 600 miles south-east of Bermuda.

Arlo Hemphill, the senior oceans campaigner for Greenpeace USA, said: “We had at least one sample that had higher amounts of plastic than anything we found in the Great Pacific Garbage Patch.”

He added: “The one sample that was greater than anything in the Great Pacific Garbage Patch had over 1,200 pieces of microplastic.”

Mr Hemphill said it was an “incredibly high” amount and was greater than any sample taken from the Great Pacific Garbage Patch, which was “worldwide famous for having massive amounts of plastic in the ocean”.

Celia Ojeda-Martinez, the consumption programme manager for Greenpeace Spain, added: “A low number of plastics would be fewer than 100 in each sample.

“We never took a sample in the Sargasso Sea with less than 1,000 pieces.”

Mr Hemphill added: “I sailed on a Greenpeace ship two years ago and we sailed from the Netherlands to New York City, far north of Bermuda.

“We did trawls every day and they were never anywhere near as high as they are here in the Sargasso Sea.”

The Greenpeace flagship Esperanza used a device called a manta trawl to sample several areas of the massive area of seaweed that gives the Sargasso Sea its name. Ms Ojeda-Martinez said: “We found more plastics in the international waters than close to the island, maybe because it has this strong current that takes away the plastic. They get brought back when you have bad weather.”

Mr Hemphill said that island researchers such as Robbie Smith, the curator at the Bermuda Aquarium, Museum & Zoo, had come up with different results.

He added: “We heard from Dr Robbie Smith that the island does have an effect of trapping plastic close to it, and that he’s encountered high numbers of plastic around the coast, but we also didn’t do sampling within five miles of Bermuda’s shores, and that’s where Dr Smith says the plastic gets trapped.”

Mr Hemphill said that plastics in the ocean was “of major concern to both ecosystem and human health”.

He explained: “From an ecosystem perspective, plastics stop ecosystems from functioning properly.

“The ecosystems of the high seas do an incredible amount for humans, from producing around 60 per cent of the oxygen we breathe to providing protection in the form of Sargassum seaweed mats to juvenile fish and other seafood that we end up eating.

Mr Hemphill added: “When turtles and birds and fish eat these plastics, they can choke and die, or their stomachs fill up with plastics instead of nutrients so they die from starvation.

“These plastics carry toxins. Plastic is a substance that attracts oil, and oil can pick up heavy metals and pesticides.

“The fish that eat the plastics absorb the toxins and they end up on our dinner plates. We don’t yet understand the effects of this on humans.”

Greenpeace conducted the research as a part of its “Protect the Oceans” global campaign.

Mr Hemphill said that the information collected was still being analysed.

He added: “Right now, we can comment on trends that we’ve observed but we’re going to have to wait for both laboratory results as well as statistical analyses to get the final answers.”

He said that the results were expected to be published by April next year.