North Korea could fire off more Musudan intermediate-range ballistic missiles (IRBM) in the near future following their string of failed launches, the Defense Ministry spokesman said Friday.

"Given that North Korea ventured to test two of its Musudan missiles after its previous failure, we cannot rule out the possibility of Pyongyang conducting more launches," Moon Sang-gyun told reporters.

On Thursday alone, North Korea attempted to launch two of its IRMBs from the vicinity of the east coastal city of Wonsan, one in the morning and one in the evening. The first veered off course and crashed into the coastal area and the other one reportedly exploded in midair.

The botched launches came despite the North's first Musudan also ended in catastrophic failure earlier in the month. On the high-profile national anniversary of founding father Kim Il-sung's birthday on April 15, the reclusive country attempted its first test-launch of the IRBM, but the projectile blew up only seconds into its flight.

The military said the second missile launched by North Korea on Thursday did manage to go up several kilometers, staying in the air for about a minute before exploding.

Experts have said the string of failed launches may give North Korea greater incentive to conduct a nuclear test in the run-up to the country's rare congress of the ruling Workers' Party of Korea, in order to save face.

"It is highly likely that North Korea would venture a nuclear test in the short run, with that in mind, the military is maintaining heightened surveillance and readiness," he said.

The spokesman added that "We assessed that North Korea has finished its preparations (for a nuclear test)." (Yonhap)