The prosecutor of the International Criminal Court has confirmed his office was starting a preliminary examination of possible war crimes by North Korea.
The United Nations probe follows complaints from South Korean students and citizens.
Luis Moreno Ocampo said that “no state requested our intervention”.
Mr Moreno Ocampo’s office announced on Monday that he had opened a preliminary investigation into the November 23 shelling of South Korea’s Yeonpyeong Island and the sinking of a South Korean warship in March, but it was unclear where the complaints came from.
He said his office would now conduct an assessment to determine whether a full-scale investigation of possible war crimes by North Korea should be carried out.
He said prosecutors must determine whether the incidents constituted war crimes, whether the court had jurisdiction, and whether the South Korean government was taking legal action.
The UN’s International Criminal Court, which began operating in 2002, is the world’s first permanent war crimes tribunal. Under the treaty, the court can step in only when countries are unwilling or unable to dispense justice themselves for genocide, crimes against humanity or war crimes.
South Korea is one of 114 countries that have ratified the Rome Treaty that established the court, but North Korea does not recognise its authority.
Mr Moreno Ocampo said the goal of the preliminary examination was “just to collect information, to understand what’s happened”.
The shelling of Yeonpyeong Island killed two South Korean marines and two civilians. Forty-six South Koreans died in the sinking of the warship, the Cheonan. Mr Moreno Ocampo’s statement on Monday said it was “hit by a torpedo allegedly fired from a North Korean submarine”.