Quoting North Korean and Japanese sources, the Asahi Shimbun said Pyongyang has already notified its intentions to the US in a secret meeting held between officials of the two nations earlier this month.
“If the United States continues its policy of pressure against us, we may be forced to take opposing measures. Such as, for example, a nuclear test,” a North Korean official is said to have told a US envoy Jack Prtchard.
The Japanese daily said the nuclear test could take place by September 9.
Communist North Korea had earlier claimed to have finished reprocessing spent nuclear fuel that could allow it to make about half a dozen atomic bombs.
The reclusive country’s suspected nuclear ambitions have been a cause for major international consternation in recent months.
It has particularly been engaged in acrimonious exchanges with the US, which accuses it of pursuing a hidden nuclear weapons programme.
Cautious hopes of a breakthrough in the crisis have however risen since China sent an envoy to Pyongyang earlier this month, apparently to push for a compromise format for negotiations.
North Korea wants direct talks with the US to resolve the crisis, while Washington insists on multilateral talks, with the participation of Japan, China and South Korea.