SEOUL, South Korea — The acting president of South Korea, Hwang Kyo-ahn, on Monday called the killing of Kim Jong-nam, the estranged half brother of North Korea’s leader, “an intolerable crime against humanity and terrorist act” masterminded by the North Korean regime.

The remarks were the strongest yet by the South Korean leadership linking the North Korean government, led by Kim Jong-un, to the brazen killing of Mr. Kim’s half brother on Feb. 13 at Kuala Lumpur International Airport in Malaysia.

In his remarks, Mr. Hwang also urged the world to hold North Korea accountable for the killing.

“It starkly demonstrated the North Korean regime’s recklessness and cruelty as well as the fact that it will do anything, everything in order to maintain its power,” Mr. Hwang said during a meeting of security-related cabinet ministers on Monday. “We need to cooperate with the international community to ensure that North Korea will pay a just price for its terrorist act.”

Mr. Hwang’s comments escalated pressure on North Korea by formally accusing Mr. Kim’s government of carrying out a terrorist attack, which could encourage other nations, including the United States, to try to punish the government in Pyongyang.