SEOUL, May 3 (Xinhua) — South Korea's military on Tuesday warned of possible nuclear test and missile launch by the Democratic People's Republic of Korea (DPRK) ahead of the country' s historic ruling party convention set to kick off on Friday.

Seoul's defense ministry submitted a report on recent DPRK situations to the parliamentary defense committee meeting, saying that the DPRK could conduct strategic provocations such as nuclear test and missile launch in and around the ruling Workers' Party of Korea (WPK) congress.

The ministry said another nuclear test can be carried out at any time in the DPRK's main Punggye-ri nuclear test site, noting that top DPRK leader Kim Jong Un may seek to praise his achievements with another nuclear test as South Korea has undervalued its fourth nuclear test.

The DPRK detonated what it claimed was its first hydrogen bomb on Jan. 6, which Seoul estimated to have been a boosted fission bomb rather than a H-bomb.

South Korean Defense Minister Han Min-koo told lawmakers during the parliamentary meeting that there is a possibility for a boosted fission bomb to be tested in the DPRK's fourth nuclear detonation, saying that no clear difference could be found between Pyongyang's third and fourth nuclear tests.

Han also said no evidence has been found that the DPRK possessed a miniaturized nuclear warhead.

Pyongyang has claimed that the country possesses a nuclear warhead, which can be mounted on a long-range ballistic missile capable of striking the U.S. mainland.

The DPRK test-fired what were believed to have been three Musudan intermediate-range ballistic missiles on April 15 and 28, but South Korea's military considered all of the tests failures as the missiles exploded in mid-air or crashed in waters several seconds after liftoff.

The DPRK announced its successful test-launch of a ballistic missile from a submarine on April 24, but Seoul saw it as a partial success as the missile flew some 30 km, very short of 300 km required to secure a stable flight test for ballistic missiles.

Seoul's defense ministry said that the DPRK could test more ballistic missiles to recover credibility of its missile system as South Korean news organizations reported on the failed missile tests.

The DPRK test-fired two Scud short-range missiles on March 10 and two Rodong ballistic missiles on March 18 amid the ongoing U.S. -South Korea annual military exercises that ended late in April.