Malaysia police have arrested a female suspect in connection with the death of Kim Jong-nam, the estranged half-brother of North Korea's leader Kim Jong-un.

Police said the woman they arrested on Wednesday carried a Vietnamese passport and was alone at the time of arrest.

The woman, detained at the low-cost terminal of the Kuala Lumpur International Airport in the Malaysian capital, was identified on the travel document as Doan Thi Huong born on May 31, 1988, police said. 

The "suspect was positively identified from the CCTV footage at the airport and was alone at the time of arrest", they added.

READ MORE: Kim Jong-nam 'poisoned with chemical spray'

Kim died on Monday after suddenly falling ill at Kuala Lumpur airport. He had been on his way to the Chinese territory of Macau, where he had been living. He was reportedly living under China's protection.

He died on his way to hospital.

An autopsy will be performed on Wednesday, police said.

Police and authorities were working with diplomats from North Korea and Vietnam to confirm whether or not the suspect is a Vietnamese citizen, local media reported.

Al Jazeera's Karishma Vyas, reporting from Kuala Lumpur, said: "In addition to this one woman they have arrested, police are looking for another female suspect and several others including four men who might be involved in the murder of Kim Jong-nam.

"Kim had lived in exile for many years and kept a low profile. He never publicly expressed interest in challenging his half-brother Kim Jong-un for the North Korean leadership, however he has been critical of the regime. He did not support the dynastic style of the political rule [and] that may have been perceived as threat."

'Brutality of Kim Jong-un regime'

South Korea's spy agency suspects two female North Korean agents assassinated Kim, South Korean MPs in Seoul have said.

"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, who is also the country's acting president, told a security council meeting.

Al Jazeera's Harry Fawcett, reporting from Seoul, said: "The National Intelligence Service here says this is a long-standing order from the North Korean leadership. There was [reportedly] an attempt in 2012 to kill him. There have long been efforts to eradicate this family member."

File: Kim Jong-nam, left, was the exiled half-brother of North Korea's leader Kim Jong-un, right [AP]

While there was speculation over the timing of the incident, the head of spy agency has said that North Korea probably just made the most of an opportunity that presented itself, said Fawcett.

Kim, 46, was targeted in the shopping concourse at the airport and had not yet gone through immigration for his flight to Macau, said a senior government official, who spoke on condition of anonymity because the case involves sensitive diplomacy. (concourse: a large space or room in a public building such as  station or airport that people meet in or pass through: 중앙홀) 익명의 고위관료에 의하면, 김정남은 출국수속 전 쇼핑홀에서 공격을 받고 사망한 것으로 보임. 이 부분은 BBC기사에는 나오지 않음.

Kim told medical workers that he had been attacked with a chemical spray, the official said. 김정남이 죽기 전, 자신이 화학물질 스프레이 공격을 받았다고 말했다고 한다.

Although Kim had been tipped by some outsiders as a possible successor to his father, others thought that was unlikely because he lived outside the country, including recently in Macau, Singapore and Malaysia. (tipped by as: ~로 예상되다)