The defense ministry has set up a large probe panel to look into what went wrong with maritime operations following revelations that a North Korean boat crossed the eastern sea border and arrived at a South Korean port undetected, officials said Friday.

The small-sized wooden boat, carrying four North Koreans, was found at the port of Samcheok, Gangwon Province, on Saturday. A South Korean civilian first spotted them and reported the case to police, sparking criticism over loopholes in South Korea's maritime and coastal defense operations.

Public criticism of the security failure worsened amid allegations that the military tried to cover it up.
 
The investigation team involves about 30 officials from the ministry and the military as well as experts in military operations, making the panel quite large, according to the officials. The panel began its probe into the case, which is to last for about a week, on Thursday, they added.

"Focus will be on whether the military's surveillance systems were operated appropriately and what caused them to fail to detect the North Korean ship," an official said. (Yonhap)