The South Korean government said Monday it will hold military drills aimed at deterring further aggression of the Democratic People's Republic of Korea and put on hold all exchanges and trade with Pyongyang.

The statements made by defense, foreign and unification ministers came in response to the recent sinking of its warship by DPRK's alleged torpedo attack.

A few hours earlier, President Lee Myung-bak said his country will resort to measures of self-defense in case of further military provocation of Pyongyang over its sinking of a South Korean warship in late March, which killed 46 sailors near disputed maritime border between the two Koreas.

Seoul is planning to hold anti-submarine drills with the United States off the west coast of the Korean peninsula, the scene of the naval tragedy, and to hold military exercises aimed at deterring proliferation of Pyongyang's weapons of mass destruction, defense minister Kim Tae-young said in a joint briefing.

The country will no longer allow DPRK-flagged vessels in the South's territorial waters and forcibly return them in case ships do not comply with the measure, while it immediately resumes anti- Pyongyang propaganda activities, Kim added.

Seoul's top diplomat Yu Myung-hwan said Seoul and its ally, Washington, will discuss at the bilateral level punitive sanctions on the DPRK, while the government seeks cooperation with regional powers including China and Russia.

The country will participate more actively in the Proliferation Security Initiative (PSI), a multinational initiative aimed at deterring proliferation of weapons of mass destruction.

South Korea will no longer allow its nationals to travel to the DPRK and ban further investment in the northern neighbor, unification minister Hyun In-taek said. The country will sever the flow of aid to the DPRK except humanitarian assistance, he said.