Seafood caught by slave fishermen is ending up in supermarkets, restaurants and pet shops across America, an investigation has found.

Burmese men are being kept in cages on a tiny Indonesian island and forced to fish - or risk being kicked, beaten and whipped with stingray tails.

Seafood caught by the slaves is entering major supply networks in the US with tainted produce appearing in sushi, canned pet food and bags of frozen fish, it is claimed.

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Slaves are being locked up in cages on a tropical Indonesian island and forced to catch fish which ends up in US supply chains

Workers in Benjina, Indonesia, load fish onto a cargo ship bound for Thailand. Seafood caught by slaves mixes in with other fish at a number of sites in Thailand, including processing plants

The Associated Press says the men were brought to the village of Benjina through Thailand and the fish they are forced to catch is shipped back to Thailand before entering the global commerce stream.

It claims tainted fish can wind up in the supply chains of some of America's major grocery stores, such as Kroger, Albertsons and Safeway; the nation's largest retailer, Wal-Mart; and the biggest food distributor, Sysco.

It can also find its way into the supply chains of some of the most popular brands of canned pet food, including Fancy Feast, Meow Mix and Iams.

There are also suggestions it can turn up as calamari at fine dining restaurants, as imitation crab in a California sushi roll or as packages of frozen snapper relabeled with store brands that land on dinner tables.

In a year-long investigation, the AP interviewed more than 40 current and former slaves in Benjina.

It charted the journey of a single large shipment of slave-caught seafood from the Indonesian village, including squid, snapper, grouper and shrimp, and tracked it by satellite to a Thai harbor.

Upon its arrival, journalists followed trucks that loaded and drove the seafood over four nights to dozens of factories, cold storage plants and the country's biggest fish market.

Captive: A security guard talks to detainees inside a cell at the compound of a fishing company in Benjina, Indonesia

Locked up: The men are forced to work 22-hour shifts or risk being kicked, beaten and whipped with stingray tails

Some fishermen, risking their lives, begged reporters for help.

'I want to go home. We all do,' one Burmese slave called out over the side of his boat, a cry repeated by many men.

'Our parents haven't heard from us for a long time, I'm sure they think we are dead.'

Their catch mixes in with other fish at numerous sites in Thailand, including processing plants. US Customs records show that several of those Thai factories ship to America.

They also ship to Europe and Asia, but the Associated Press traced shipments to the US, where trade records are public.

The major corporations identified by AP declined interviews but issued statements that strongly condemned labor abuses. Many described their work with human rights groups to hold subcontractors accountable.

National Fisheries Institute spokesman Gavin Gibbons, speaking on behalf of 300 US seafood firms that make up 75 percent of the industry, said his members are troubled by the findings.

'It's not only disturbing, it's disheartening because our companies have zero tolerance for labor abuses,' he said. 'These type of things flourish in the shadows.'

The slaves interviewed by the AP described 20 to 22-hour shifts and unclean drinking water.

Almost all said they were kicked, beaten or whipped with toxic stingray tails if they complained or tried to rest. They were paid little or nothing.

An investigation suggests seafood caught by the slaves is ending up in major supply networks in the US with tainted produce appearing in sushi, canned pet food and bags of frozen fish

A refrigerated cargo ship called the Silver Sea Line, second from right, is docked at Thajeen Port in Thailand, 15 days after it set sail from Benjina, Indonesia with a load of wild-caught seafood

Runaway Hlaing Min said many died at sea.

'If Americans and Europeans are eating this fish, they should remember us. There must be a mountain of bones under the sea,' he said.

'The bones of the people could be an island, it's that many.'

In the small harbor in the village is a five-story office compound which includes the cage with the slaves, AP reports.

At the Benjina port, the AP interviewed slaves from a dozen fishing vessels offloading their catch into a large refrigerated cargo ship, the Silver Sea Line.

The ship belonged to the Silver Sea Reefer Co., which is registered in Thailand and has at least nine refrigerated cargo boats. The company said it is not involved with the fishermen.

'We only carry the shipment and we are hired in general by clients,' said company owner Panya Luangsomboon. 'We're separated from the fishing boats.'

AP followed that ship, using satellite tracking over 15 days to Samut Sakhon, Thailand, and journalists watched as workers packed the seafood over four nights onto more than 150 trucks, following deliveries to factories around the city.

Slaves from Myanmar lean over the deck of their fishing trawler. Many of the men were brought to the village of Benjina through Thailand

Frozen seafood is off-loaded from a refrigerated 3,000-ton cargo ship in Thailand. The ship belongs to the Silver Sea Reefer Co. but the company said it is not involved with the slave fishermen

Inside those plants, representatives said they sold seafood to other Thai processors and distributors. US Customs bills of lading identify specific shipments from those plants to American firms, including well-known brand names.

For example, one truck bore the name and bird logo of Kingfisher Holdings Ltd., which supplies frozen and canned seafood around the world.

Another truck went to Mahachai Marine Foods Co., a cold storage business that also supplies Kingfisher, according to Kawin Ngernanek, whose family runs it.

'Yes, yes, yes, yes,' said Kawin, who also serves as spokesman for the Thai Overseas Fisheries Association. 'Kingfisher buys several types of products.'

When later asked about abusive labor practices, Kawin was not available.

Instead, Mahachai Marine Foods manager Narongdet Prasertsri responded: 'I have no idea about it at all.' Kingfisher did not answer repeated requests for comment.

Every month, Kingfisher and its subsidiary KF Foods Ltd. sends about 100 metric tons of seafood from Thailand to America, according to US Customs records.

Slaves use this warehouse in Benjina as a makeshift dormitory after finishing shifts that last up to 22 hours

Workers from Myanmar load fish onto a Thai-flagged cargo ship in Benjina, Indonesia. An investigation has suggested seafood caught by the slaves is ending up on plates across America

Maung Soe of Myanmar holds up a copy of the seafarer's book given to him before he boarded a Thai fishing trawler, in Benjina, Indonesia

Tun Lin Maung sits with a group of slave fishermen from Myanmar behind a fishing company building. He says it has been two years since he escaped from the fishing trawler he was working on

These shipments have gone to Stavis Seafoods, a Boston-based Sysco supplier, and other distributors.

'The truth is, these are the kind of things that keep you up at night,' said CEO Richard Stavis, whose grandfather started the company.

He said his business visits international processors, requires notarized certification of legal practices and uses third-party audits.

'There are companies like ours that care and are working as hard as they can,' he said.

A similar pattern repeats itself with other companies and shipments.

The AP followed another truck to Niwat Co., where part owner Prasert Luangsomboon said the company sells to Thai Union Manufacturing.

Weeks later, when confronted about forced labor in their supply chain, Niwat referred several requests for comment to Luangsomboon, who could not be reached for further comment.

Thai Union Manufacturing Co. is a subsidiary of Thai Union Frozen Products PCL., Thailand's largest seafood corporation, with $3.5billion in annual sales.

This parent company, known simply as Thai Union, owns Chicken of the Sea and is buying Bumble Bee, although the AP did not observe any tuna fisheries.

Thai Union says its direct clients include Wal-Mart, and ships thousands of cans of cat food to the U.S. every month, including household brands like Fancy Feast, Meow Mix and Iams.

These end up on shelves of major grocery chains, such as Kroger, Safeway and Albertsons, as well as pet stores.

Hla Phyo stands next to a grave marker of a man he helped bury - a Burmese fisherman slave who died on a fishing boat - at a cemetery in Benjina

A group of former slaves from Myanmar, who worked on fishing ships, walk in the densely forested interior of an island in the Arafura Sea after escaping from Benjina

Free: A former slave from Myanmar, who goes by the name Mozet (centre) is one of those who escaped or ran away while trawlers were docked at the Benjina port

Again, however, it's impossible to tell if a particular can of cat food might have slave-caught seafood.

Thai Union said it takes multiple stakeholders to eradicate labor abuses.

'We all have to admit that it is difficult to ensure the Thai seafood industry's supply chain is 100 percent clean,' Thai Union CEO Thiraphong Chansiri said in an emailed statement.

The enslaved fishermen on Benjina had no idea where the fish went, only that it was too valuable for them to eat. Their desperation was palpable.

A crude cemetery holds more than 60 graves strangled by tall grasses and jungle vines.

The small wooden markers are neatly labeled, some with the falsified names of slaves and boats. Only their friends remember where they were laid to rest.

In the past, former slave Hla Phyo said, supervisors on ships simply tossed bodies into the sea to be devoured by sharks.

But after authorities and companies started demanding that every man be accounted for on the roster upon return, captains began stowing corpses alongside the fish in ship freezers until they arrived back in Benjina.

'I'm starting to feel like I will be in Indonesia forever,' said Phyo, wiping a tear away.