Darusman traveled Wednesday to South Korea as part of a three-day fact-finding mission. He's part of a commission tasked with investigating violations related to torture, arbitrary detention, the right to life, enforced disappearances and the right to food, among other things.
He said the North Korean government has so far refused to cooperate with his efforts. There are also external factors related to security tensions on the Korean Peninsula that add another layer of difficulty to his mandate.
"Unless these factors are taken into account, there will be no meaningful steps towards a gradual settlement of the Korean question, which has a direct bearing on the human rights of the people on the Korean peninsula," he said in a statement Friday.
North Korea is suspected of favoring its military and nuclear program over the welfare of its people.
"The people who are suffering from gross human rights violations in [North Korea] require immediate attention," he said.
Darusman said he regrets he's been unable to visit North Korea despite repeated requests.