By Na Jeong-ju
Staff Reporter
The military denied a media report Sunday that the Navy received a message concerning an ``unusual situation'' on the frigate Cheonan at 9:15 p.m. on March 26 just minutes before it sank near the sea border with North Korea, saying the ship and the naval command held ordinary radio communications at 9:19 p.m.
On Saturday, MBC reported, citing a military source that the 2nd Navy Fleet, to which the Cheonan belonged, reported an unusual situation on the ship to Navy headquarters at 9:15 p.m. Minutes later, the ship disappeared from radar and the Navy couldn't get a radio signal anymore, it said.
The military announced last week that the ship sank at 9:22 p.m. following an unexplained explosion, saying it would detail the exact cause of the disaster after inspecting the wreckage of the sunken vessel.
During a press conference, Lt. Gen. Park Jung-i, the chief investigator into the incident, denied the report, saying radio traffic between the Cheonan and naval command was normal.
``This means nothing unusual had taken place before 9:19 p.m.,'' Park said. ``The report was based on erroneous information.''
The military has changed the time of the explosion three times after originally announcing that it occurred at 9:45 p.m. on March 26. Later, the Navy said it took place at 9:30 p.m., then 9:25 p.m. and finally 9:22 p.m. But the Coast Guard claim the blast occurred at 9:15 p.m.
The mother of one of the missing sailors alleged earlier that she was talking to her son over phone that night.
The sailor hurriedly hung up at 9:16 p.m. saying something unusual had happened on the ship, according to the mother.
The report came amid rampant speculation over the exact cause of the disaster.
The Ministry of National Defense has rejected requests to disclose the content of radio contact between the Cheonan, the 2nd Navy Fleet headquarters in Pyeongtaek, Gyeonggi Province, and another nearby warship, saying they were confidential.
Local media have reported that the warship might have been conducting clandestine operations, such as repelling North Korean mini-submarines, at the scene, and it might have been hit by a torpedo or a mine.
Yonhap News Agency reported Saturday that the defense ministry has formed a joint military-civilian investigation team to help determine why the 1,200-ton vessel sank, citing anonymous sources.
The team has checked the Korea Naval Tactical Data System (KNTDS) to determine the exact movement of the Cheonan prior to the explosion.
KNTDS, operated by the naval tactical command in Busan, receives and processes information from all South Korean warships operating around the Korean Peninsula.
The data provides real-time information on such details as a ship's heading and speed that can be used by commanders to make important decisions.
The system, in addition, receives feedback from shore-based radar stations that help determine the movement of North Korean ships.
``Because the system shows when one of our ships stop moving, it can be used to discover exactly when and why the Cheonan was lost,'' a defense ministry spokesman said.
He however said it is impossible to release the KNTDS data to the public due to security concerns.
The ministry said Thursday that there was an explosion measuring as powerful as about 1.5 on the Richter scale at the site where the Cheonan sank, citing a report from a state geological survey institute.
A magnitude 1.5 earthquake would equal 180 kilograms of TNT. Some experts claimed such an explosion might have been caused by a torpedo attack or sea mine.