South Korea is planning to seek an additional resolution on the Democratic People's Republic of Korea at the United Nations Security Council, following the sinking of South Korea's warship Cheonan in March, South Korea's Yonhap news agency reported Sunday quoting officials.

"We are focusing on diplomatic means of punishment as we found out that existing sanctions and resolutions are not enough," a senior government official told Yonhap News Agency. "It is time to decide whether we go over to another step."

Another official at the presidential office also hinted at bringing the case to the U.N. Security Council and seeking a fresh resolution, adding, "It is logical to give a number to a resolution based on the Council's menu."