Police are looking into a Malaysian business that had used North Korean workers to build houses in Africa, as part of the allegations that North Korea has violated international sanctions through Malaysian businesses.

The Wall Street Journal (WSJ) reported today that the North Korean director of the company travels in North Korean diplomatic vehicles when he is in Malaysia and Africa, according to a person familiar with the company's activities.

"The company has earned tens of millions of dollars or more on construction projects in Angola and Zambia over the past decade, according to two analysts who separately evaluated the company's business operations.

"The company has strong ties to the North Korean government, according to several North Korea experts, including one of the analysts, Park Syung-je, chairperson of the Asia Strategy Institute, a Seoul research centre," WSJ reported.

A human rights group said that North Korean labourers employed by the company in Africa are usually required to return most of their earnings to North Korea as a condition for going abroad, WSJ reported.

The US daily said employees at the company's Kuala Lumpur headquarters declined to reply on this matter and attempts to reach the holding company's director and his Malaysian business partner were not successful.

"The United Nations (UN) is examining the company for possible violations of sanctions against North Korea and has pressed Malaysia to look into the company and others.

"The UN originally raised concerns about the company’s operations in 2014; it raised those concerns again in a February report, and said the Malaysian government hadn’t responded to its latest queries," WSJ said.

Malaysia previously had friendly relations with North Korea, though that has soured after the Feb 13 assassination of Kim Jong-nam, the estranged half-brother of North Korean leader Kim Jong-un, in Malaysia.

The police have named several North Korean suspects in Jong-nam's murder, and the Malaysian government had expelled the North Korean ambassador.

In retaliation, North Korea banned Malaysians in the country from leaving.

WSJ said a Malaysian government spokesperson declined to comment on the investigations into possible violations of sanctions, while calls to the North Korean embassy in Malaysia went unanswered.

Malaysiakini is unable to independently verify this WSJ report.