North Korea has arrested a fourth official over the failed launch of a new warship that has enraged the country's leader, Kim Jong Un. Ri Hyong-son, deputy director of the ruling Workers' Party's Munitions Industry Department, was "largely responsible for the serious accident" last week, state-run news agency KCNA said on Monday.

North Korean authorities have detained four officials over the recent failed launch of a naval destroyer, an incident that leader Kim Jong Un said was caused by criminal negligence, state media said.