"I think the China variable and the COVID-19 variable are playing into this," the official was quoted as saying by Yonhap.
The preparation of the seventh North Korean nuclear test has been reported for weeks, with the remaining last step being the decision of leader Kim Jong Un. However, the country has been putting off the final step because of the upcoming 20th National Congress of the Chinese Communist Party in autumn, the news agency said.
"It appears that North Korea is making a considerable effort out of concern for the major chaos that would be caused by a seventh nuclear test, although we haven't been able to verify it," the official was quoted by Yonhap as saying.
China is one of the few major political allies that has been supporting and providing financial aid to North Korea. A nuclear test ahead of China's key political event could negatively affect the relationship between the two countries.
COVID-19 has also affected Pyongyang's decision to postpone the nuclear tests. In May, North Korea reported its first coronavirus outbreak, as several citizens tested positive for the Omicron BA.2 variant, and introduced an "emergency anti-epidemic system of the highest level."