North Korea has detained three people over an accident that occurred during the launch of a new warship this past week, state media reported early Sunday.

North Korean leader Kim Jong Un had vowed to punish those found responsible for the mishap, which he called a "criminal act caused by absolute carelessness".

SEOUL (Reuters) -North Korea has begun a full-scale investigation into the accident that occurred during the launch of a warship earlier this week, state media KCNA reported on Friday. KCNA previously said the incident was caused by a loss of balance while the vessel was being launched and sections of the bottom of the warship were crushed.