The South Korean military on Sunday stepped up its efforts to rescue 46 missing sailors from the warship that sank later Friday in waters off the west coast of the Korean Peninsula, but the operation has not made any progress.

Members of South Korean Navy's Ship Salvage Unit (front) on a rubber boat and a naval patrol ship patrol to rescue possible survivors from sunken naval ship Cheonan off Baengnyeongdo, an island near the border with North Korea, March 27, 2010. [Xinhua/Reuters Photo]

According to the state-run broadcaster KBS, an 86-member Navy rescue team has launched underwater operations earlier the day, trying to determine the exact location of the sunken ship and confirm whether there are some survivors.

After repeated failures caused by rough waves and low temperature, the military divers finally located the front of the ship around 19:57 p.m. local time. The ship is believed to have been split into two by an unexplained explosion.

Meanwhile, a 3,000-ton search-and-rescue vessel and two 700-ton minesweepers equipped with sonar detection equipment also have been sent to the scene of the incident to help the operations of the diver team.

There are a total of 104 crew members onboard when the ship sank, only 58 of them have been rescued, the other 46 remain missing though rescue efforts continue. The underwater investigation also has not yield any progress due to bad conditions such as high waves and strong winds in the area.

The KBS quoted a military official as saying that the incident might result in significant casualties because most of the crew members were likely asleep or resting inside the ship when the explosion took place at around 21:45 p.m. local time, just 15 minutes ahead of the ship's bedtime.

The sailors' bedrooms are in the lower back part of the ship, close to where the explosion occurred, and water likely entered the ship quickly after the explosion, he said.

Although the hopes seem dimming over the rescue of the missing sailors, the related operation will continue on Monday.

A U.S. warship will be sent to the waters to join the rescue operation on Monday, and the South Korean Navy's 14,000-ton Dokdo, Asia's largest helicopter carrier, will also take part in the search and rescue operation late Monday, Seoul's Yonhap News Agency quoted military officials as saying.

The exact cause of the incident has yet to be pinpointed, government officials said, noting that it can be determined only after the sunken ship is salvaged, which will need about one month.

President Lee Myung-bak on Sunday convened a fourth meeting of security-related ministers at the presidential office of Cheong Wa Dae, demanding for thorough investigation and releasing all of the probe results to the public so as not to leave any room for suspicions for the incident.

Lee also said the most important thing at this moment is to rescue more survivors, urging the government agencies to save more lives by all means based on the belief that our sailors are still alive.

Prime Minister Chung Un-chan paid an inspection to the island of Baekryeongdo, the closest island to the scene of the warship sinking. He pledged to mobilize all available resources and provide full support to help rescue operation and determine the cause of the incident, according to Yonhap.