Female assassins killed half-brother of North Korea's Kim Jong Un, suspects South Korea

South Korea's spy agency suspects two female North Korean agents assassinated the estranged half-brother of North Korean leader Kim Jong Un in Malaysia, lawmakers in Seoul said on Wednesday, as Malaysian medical authorities sought a cause of death.

South Korean intelligence believed Kim Jong Nam was poisoned, lawmakers said after being briefed by the country's spy agency.  They said the spy agency told them that the young, unpredictable North Korean leader had issued a "standing order" for his half-brother's assassination, and that there had been a failed attempt in 2012.

Lee Cheol Woo, chairman of South Korea's National Assembly Intelligence Committee, told a press briefing that Kim had been poisoned, but he did not say how. It's not clear how he obtained that information. Police have described the incident as a 'sudden death', pending the results of a postmortem investigation.

According to the spy agency, Kim Jong Nam had been living with his second wife in the Chinese territory of Macau, under Beijing's protection, the lawmakers said. One of them said Kim Jong Nam also had a wife and son in Beijing. Portly and gregarious, Kim Jong Nam had spoken out publicly against his family's dynastic control of the isolated state.

"If the murder of Kim Jong Nam was confirmed to be committed by the North Korean regime, that would clearly depict the brutality and inhumanity of the Kim Jong Un regime," South Korean Prime Minister Hwang Kyo-ahn, the country's acting president, told a security council meeting.

The meeting was called in response to Kim Jong Nam's mysterious death, news of which first emerged late on Tuesday.