SEOUL -- The Democratic People's Republic of Korea (DPRK) has the capability to build uranium-based nuclear bombs, Republic of Korea's defense chief said Wednesday, according to local media reports.

"We assess that (the DPRK) came to the level where nuclear weapons can be built with uranium," Defense Minister Kim Kwan-jin told lawmakers during the interpellation session at the headquarters of the National Assembly.

Touching on the restarted 5-megawatt reactor in the DPRK's Yongbyon nuclear complex, Kim said that Pyongyang was conducting a test operation, noting that Seoul was closely monitoring whether it will start an active operation.

His unusual comments came five days after the country's vice defense minister said Pyongyang seemed to be prepared to conduct its fourth nuclear test at any time.

Baek Seung-joo said that the southern tunnel of the underground test site in the DPRK's northeastern region of Punggye-ri can be used for another nuclear test at any time, adding that no signals have been found that the test is imminent.

The western tunnel, where the third nuclear test was conducted in February, was being renovated, Baek said.

The country's spy agency confirmed on Oct 8 that the DPRK has restarted the 5-megawatt plutonium-producing reactor in the Yongbyon nuclear complex since around August of this year.