The rear part of a South Korean warship that sank off the west coast of the Korean peninsula was located Sunday night and a buoy was installed there Monday morning, but 46 sailors aboard remained missing, Defense Ministry told a news briefing Monday.

A South Korean Navy rescue vessel Gwangyang (back) and a naval patrol ship search for possible survivors and bodies from the sunken naval ship Cheonan, in the waters off Baengnyeongdo, an island near the border with DPRK March 29, 2010. [Xinhua/Reuters Photo]

Some of the missing sailors are believed to be trapped in the bedrooms in the back of the ship which split in half late Friday and sank near the disputed sea border between the two Koreas.

The front of the vessel was also detected and a buoy was attached there, the ministry previously said.

"As the location of the stern of ship in which missing crewmen are presumed to be trapped has been spotted, all available personnel and equipment must be mobilized to search it as rapidly as possible," President Lee Myung-bak said after he received an emergency briefing from aides, according to the presidential office Cheong Wa Dae spokeswoman Kim Eun-hye.

In one of the country's worst naval disasters, the 1,200-ton warship with 104 crew members onboard sank late Friday night near the country's northernmost island of Baekryeong after an unknown explosion in the back of the ship made a hole in the bottom of it.

Only 58 crew members were rescued alive as of early Saturday morning, and continued rescue efforts throughout the weekend has made no progress.

Officials remain cautious about giving a clear explanation about the cause of the incident.

"It's hard to conclude what was behind the incident, as we need to see in what form the body of the ship was torn apart," an official at Joint Chiefs of Staff told reporters.

As weather conditions have generally improved Monday despite high currents in the Yellow Sea that hampered operations during the weekend, two rounds of search and rescue operations are planned in the afternoon, he said.