South Korea will ask North Korea to further investigate the shooting death of one of its officials, as public and political outrage over the killing grew.

After a national security council meeting on Friday, South Korea said on Saturday that it would call for a joint probe into the case with the North if needed, saying there were discrepancies in accounts of the accident from the two sides.

South Korea’s military said on Thursday that North Korean soldiers killed the man, doused his body in fuel and set it on fire near the sea border.

But the North Korean government said in a message on Friday that its soldiers shot the “illegal intruder” and denied burning his body.

In the message, North Korean leader Kim Jong-un was quoted as offering an apology for disappointing his counterpart, Moon Jae-in, and the South Korean people.

The main South Korean opposition People Power party said on Saturday that Kim’s apology was not genuine, and that the case should be sent to the International Criminal Court and the UN security council.

The Moon government faces intense political pressure over how it responded to the incident, which coincided with a renewed push by the president for engagement with Pyongyang.

Critics accused Moon of failing to save a citizen’s life and being soft on North Korea, saying the military did not attempt to save him despite spotting him six hours before he was shot dead.

The government official was reported missing while on duty on a fisheries boat near the island of Yeonpyeongdo close to South Korea’s sea border.

South Korea’s military said the man was apparently attempting to defect to the North, but his brother refuted the claims, saying that he must have had an accident.