China and Pyongyang agreed several years ago to allow factories to contract North Korean workers as bargain-priced labour in an effort to boost the local economy.
According to the investigation products made by North Korean workers have been traced to the US, part of Europe and Canada, the Business Insider reports.
The North Korean’s working abroad are required to pay Kim Jong-un’s regime up to 70 per cent of their wages and it is estimated that the despotic regime collects a revenue of between £151million ($200million) and £377million ($500million) a year from the slave labour.
It comes as the dictator is building up his nuclear arsenal with frequent missile launches and a hydrogen bomb test last month.
John Connelly, president of the National Fisheries Institute, the largest seafood trade association in the US, said his group was urging all of its companies to re-examine their supply chains “to ensure that wages go to the workers, and are not siphoned off to support a dangerous dictator”.
He added: “While we understand that hiring North Korean workers may be legal in China.
“We are deeply concerned that any seafood companies could be inadvertently propping up the despotic regime.”
The investigation alleges seafood could be tracked to supply chains used by Walmart and Aldi.
Under a recent law passed by Donald Trump US companies are not allowed to import products made by North Korean workers anywhere in the world as the President continues to engage in a war of words with Kim Jong-un.
Earlier this week Trump declared that the time for talking with “Little Rocket Man” was over as he hinted at military action amid World War 3 fears.
The President tweeted: “I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man.
“Save your energy Rex, we’ll do what has to be done!”
North Korea later hit back on the 64th anniversary of the Mutual Defence Treaty between the US and Seoul accusing Washington of orchestrating an “invasion plot”.
Despotic leader Kim Jong-un used his puppet newspaper, Rodong Sinmun, to take aim at the treaty on Sunday.
The Rodong Sinmun described the agreement as: “A treaty embedded with a plot to actualise their delusion to invade North Korea.”
The paper added: “The Mutual Defence Treaty is explicitly implanted with the US’ reckless ambition for invasion as it aims to trigger a war of invasion into North Korea at any time.
“The invasion war treaty should be abolished without delay.”
The Mutual Defence Treaty states that if either the US or South Korea is faced with an external armed attack – the other will come to the attacked country’s aid.