South Korea’s spy agency Wednesday confirmed the killing of North Korean leader Kim Jong-un’s half-brother, saying Kim Jong-nam had faced murder attempts for the past five years that prompted him to “beg for mercy.”

Kim, 46, asked for help while queuing to board a flight to Macau at the international airport in Kuala Lumpur at around 9 a.m. on Monday, after two women approached to poison him, National Intelligence Service Director Lee Byung-ho told lawmakers, citing CCTV footage. He was pronounced dead on his way to a nearby hospital and the suspects, who the agency said took off in the same taxi after the attack, were likely to be North Korean operatives and still in Malaysia.

In Malaysia, local media reports said authorities arrested two women from Vietnam and Myanmar respectively later in the day. State-run Bernama said the Myanmar woman was caught at the airport’s low-cost terminal, citing the police deputy inspector general. The Sun Daily said the Vietnamese woman in her 20s was also nabbed at the airport by detectives on duty, and she was among six suspects -- two women and four men -- being sought after by police, citing unnamed sources.

The UK’s Telegraph reported the women were Vietnamese and that a senior diplomat from Pyongyang had requested an autopsy not to be conducted on Kim, though the request was denied. It cited a Malaysian police official after the arrest of the taxi driver who ferried the women out of the airport.

Seoul officials said they could not confirm the reports.

“The assassination of Kim Jong-nam had been a ‘standing order’ since Kim Jong-un took power,” Rep. Kim Byung-kee of the Democratic Party of Korea told reporters after a closed-door session with the spy chief, adding that a full-fledged attempt was made in early 2012.

“In April 2012, Kim Jong-nam sent a letter to Kim Jong-un, begging for mercy for him and his family and saying they have no place to go and hide out, and they know well that the only way to run away is to commit suicide.

Kim was believed to have a fake passport as he often did in the past. Malaysian police confirmed the death of a North Korean man identified with his travel document as Kim Chol, born in Pyongyang in 1970.

The NIS assessed that multiple agencies may have been involved but the Reconnaissance General Bureau could be the chief engineer. His first wife and son live in Beijing, and his second wife, son and daughter in Macau, under the protection of the Chinese authorities.

But the agency denied speculation that the deceased Kim could have sought to defect to South Korea, the lawmaker said, adding he had never made such an attempt.

“(The killing) reflects Kim Jong-un’s monomaniacal personality rather than the calculation that (Kim Jong-nam) posed a threat to his rule,” said Rep. Lee Cheol-woo of the Liberty Party who chairs the parliamentary intelligence panel.

With Kim’s body set for an autopsy, speculation abounds about the pair’s identities and whether they used a poison gun, pen or spray.

“Investigation is in progress and a post mortem examination request has been made to ascertain the cause of death,” an earlier police statement said.

Beijing’s Foreign Ministry refrained from commenting on Kim’s death and his family’s whereabouts. Its spokesman Geng Shuang simply referred to the ongoing probe in Malaysia, saying China is closely monitoring the developments during a news briefing later in the day.

In Seoul, officials are striving to analyze the incident’s implications such as if it is a sign of instability within the reclusive regime.

Acting President and Prime Minister Hwang Kyo-ahn convened a meeting of the National Security Council early Wednesday, calling for watertight readiness and vigilance against any possible provocation.

“If the murder of Kim Jong-nam was confirmed to be committed by the North Korean regime, it would plainly illustrate the Kim Jong-un regime’s brutality and inhumanity,” Hwang said at the session.

Foreign Minister Yun Byung-se, shortly before his departure for Germany, said he expects to discuss the incident as well as the North’s nuclear issues at the Group of 20 ministerial meeting and Munich Security Conference later this week.

The government also scaled up security for high-profile North Korean defectors including Thae Yong-ho, a former minister at the North Korean Embassy in London, and Park Sang-hak, head of the Fighters for Free North Korea, who faced death threats from secret agents in the past.

“We carried out a situation review last night and today on the personal safety system for the defectors and inter-Korean exchange groups, and will continue to urge their caution,” Unification Ministry spokesperson Jeong Joon-hee said, citing previous cases of assassination attempts.

By Shin Hyon-hee (heeshin@heraldcorp.com)