Two US nationals have been sentenced to lengthy prison terms for their role in a covert scheme that defrauded major American companies and generated millions of dollars for North Korea, the US Justice Department said on Wednesday.

Zhenxing “Danny” Wang, 39, and Kejia “Tony” Wang, 42, both based in New Jersey, were sentenced by a federal court in Boston to more than seven and nine years in prison, respectively, after pleading guilty to charges linked to the operation, CNN said in a report.

According to prosecutors, the pair acted as intermediaries in a sophisticated network that enabled overseas technology workers — linked to North Korea — to secure employment with leading US firms using stolen identities of American citizens.

Central to the scheme were so-called “laptop farms,” in which company-issued computers were maintained at US locations to create the appearance that the workers were operating domestically.

This allowed foreign operatives to remotely access corporate systems, receive salaries, and, in at least one case, obtain sensitive export-controlled data from a defence contractor.

Authorities said several companies, including a semiconductor distributor and a software firm, unknowingly paid the workers.

US officials have warned that North Korea is increasingly relying on such tactics to bypass international sanctions and generate revenue for its weapons programmes.

The Justice Department said the network involved the use of front companies to falsely legitimise employment, while stolen identities of at least 80 Americans were used to facilitate hiring.

Experts say such operations are becoming more sophisticated, with facilitators exploiting US-based entities and recruitment systems to evade detection.

Washington has stepped up efforts to counter the threat, including offering rewards for information on individuals involved in similar schemes, as concerns grow over North Korea’s use of cyber and IT infiltration to fund its activities.