South Korean officials are narrowing down the possibilities that the Democratic People's Republic of Korea (DPRK) is involved in a South Korean navy patrol ship sinking, according to local media Saturday.

Likelihood of the DPRK's involvement in the incident seems low, Seoul's Yonhap News Agency quoted multiple officials at the Presidential Office of Cheong Wa Dae as saying.

"It is hard to say for sure now, but chances appear to be slim that North (DPRK) was related," a senior official told Yonhap on the condition of anonymity.

There has been no unusual movements by the DPRK so far, Cheong Wa Dae spokeswoman Kim Eun-hye said at a press briefing after President Lee Myung-bak convened a second emergency meeting with security officials earlier Saturday.

The South Korean naval vessel, with 104 crew members onboard, sank into waters off the west coast of the Korean Peninsula late Friday due to an unknown cause.

The 1,200-ton ship sank off the South Korean island of Baekryeongdo off the west coast at around 21:45 p.m. Friday local time (1245 GMT Friday), with an explosion in the back of the ship.

President Lee Myung-bak on Saturday demanded a "quick and thorough" investigation, and called for rescuing the missing by all means.

Lee also ordered to inform related nations engaged in the six- party talks of proper information about the incident, and urged government agencies to take measures to reassure the public.