A North Korean defector reported that the chief of Bureau 131 in the North’s ruling Worker’s Party might have been executed.
Bureau 131 is known to be responsible for building the North’s key military facilities.
These include portals for the Punggye-ri nuclear test site and facilities for the Dongchang-ri missile launch site.
The sixth test was originally scheduled for spring but was delayed to September.
The report said the official was probably purged for the delay and also the collapse of the underground tunnels at the Punggye-ri nuclear site.
Around 200 died after the Punggye-ri nuclear site collapsed.
It comes as Donald Trump’s Homeland Security advisor officially blamed North Korea for unleashing a cyberattack that crippled hospitals, banks and other companies across the globe earlier this year.
Kim Jong-un’s regime has long been suspected of the WannaCry cyber attack which targeted 150 countries and sent many of the UK’s NHS hospitals into meltdown.
The White House’s Homeland Security advisor Thomas Bossert said: “The US today publicly attributes the massive ‘WannaCry’ cyberattack to North Korea.
“We do not make this allegation lightly. It is based on evidence.
“While victims received ransom demands, paying did not unlock their computers. It was cowardly, costly and careless. The attack was widespread and cost billions, and North Korea is directly responsible.
“Other governments and private companies agree. The United Kingdom attributes the attack to North Korea, and Microsoft traced the attack to cyber affiliates of the North Korean government.”
A former US ambassador to the UN has warned that Trump must attack North Korea soon to wipe out its nuclear threat.
But he said the President would not be able to ignore the threat for much longer as Pyongyang’s military ambitions showed no sign of ending.
Speaking at a Republican dinner in Asheville, North Carolina, he said “nobody” wanted World War 3 to break out.
But he claimed: “I will just say this. The president of the United States’ first duty is to protect Americans.
“You have to make the choice at some point whether the risks are greater in preventing North Korea from getting the capability of blackmailing or actually attacking the United States against the dangers of, the consequences of, a pre-emptive strike.”
This week, a North Korean spy was caught trying to sell components of weapons of mass destruction, police in Australia claimed.
Police confirmed the arrest of Chan Han Choi, 59, who has now been charged with two counts of attempting to sell missiles and with another four under legislation enforcing United Nations and Australian sanctions against North Korea.
The suspect was arrested for attempting to sell WMD related equipment and warheads, including software for the guidance systems of ballistic missiles.
The charges are the first of their kind to be brought in Australia as tensions between Pyongyang and the rest of the west heat up.