Malaysian authorities have detained a woman over the suspected assassination of Kim Jong-nam, the half-brother of North Korean leader Kim Jong-un.

Key points: Police say they arrested a woman with Vietnamese travel papers stating she was 28 years old, born in Nam Dinh

Police say they arrested a woman with Vietnamese travel papers stating she was 28 years old, born in Nam Dinh North Korean officials in Malaysia object to an autopsy, request body be returned

North Korean officials in Malaysia object to an autopsy, request body be returned Kim told medical workers before he collapsed he had been attacked with chemical spray

Kim told medical workers before he collapsed he had been attacked with chemical spray Local media reports said two North Korean agents were responsible for Kim's death

The Royal Malaysia Police issued a statement saying they had arrested a woman who was carrying Vietnamese travel documents that said she was born on May 31, 1988 in the city of Nam Dinh.

Police said the woman was detained in the Kuala Lumpur International Airport (KLIA).

"[The] suspect was positively identified from the CCTV footage at the airport and was alone at the time of the arrest," a statement read.

Local media had earlier published a grainy CCTV-captured image of a woman wearing a white shirt with the letters 'LOL' on the front.

A CCTV still showed a woman, believed to be connected to Kim's death, wearing a 'LOL' shirt. ( AP/Star TV )

"Police are looking for a few others, all foreigners," Deputy Inspector-General Noor Rashid Ibrahim said, declining to give their nationalities or gender.

North Korean Government officials in Malaysia objected to an autopsy being performed on Kim's body, requesting that it be immediately released back to them.

Kim, 46, collapsed on Monday in the shopping concourse at the airport and had not gone through immigration yet for his flight to Macau.

He was taken to the airport clinic and then died on the way to the hospital, an official said.

Kim told medical workers before he died that he had been attacked with a chemical spray, believed to have been administered by one or two female suspects.

"The deceased … felt like someone grabbed or held his face from behind," police official Fadzil Ahmat said.

"He felt dizzy, so he asked for help at the … counter of KLIA."

Kim Jong-nam was estranged from his younger brother, North Korean leader Kim Jong-un.

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

He reportedly fell further out of favour when he was caught trying to enter Japan on a false passport in 2001, saying he wanted to visit Tokyo Disneyland.

South Korea's spy service, the National Intelligence Service, said that North Korea had been trying for five years to kill Kim Jong-nam, citing the leader's alleged "paranoia" about his half-brother.

'Female agents' reportedly behind assassination

Security personnel at the hospital Kim Jong-nam was taken to after collapsing at an airport. ( AP: Vincent Thian )

Multiple South Korean media reports said Kim Jong-nam was killed at the airport by two women believed to be North Korean agents, who fled the airport in a taxi.

A Malaysian police statement confirmed the death of a 46-year-old North Korean man whom it identified from his travel document as Kim Chol, born in Pyongyang on June 10, 1970.

"Investigation is in progress and a post-mortem examination request has been made to ascertain the cause of death," the statement said.

Ken Gause, from the Centre for Naval Analyses think tank in Washington, has studied North Korea's leadership for 30 years and said Kim Chol was a name that Kim Jong-nam had travelled under.

Kim is believed to have been born on May 10, 1971, although birthdays are always unclear for senior North Koreans, Mr Gause said.

Although there was scant evidence that Kim Jong-nam was plotting against the North Korean leader, he provided an alternative for North Koreans who would want to depose his brother.

The killing comes as North Korea celebrated its latest missile launch, which foreign experts were analysing for evidence of advancement in the country's missile capabilities.

For the next several days, North Korea will be marking the birthday of its late leader Kim Jong-il, the brothers' father.

North Koreans are paying tribute to former leader Kim Jong-il, who was born on February 16. ( Reuters: Kyodo - file )

Timeline of suspected NK killings 1968: Commandos, dressed as SK military, attempt to assassinate President Park Chung-hee. Stopped 800 metres from the Blue House, 29 of 31 would-be assassins were killed.

Commandos, dressed as SK military, attempt to assassinate President Park Chung-hee. Stopped 800 metres from the Blue House, 29 of 31 would-be assassins were killed. 1974: Suspected NK agent shoots at Park during Independence Day speech, missing and instead killing his wife.

Suspected NK agent shoots at Park during Independence Day speech, missing and instead killing his wife. 1983: Bomb explodes at Myanmar memorial during SK President Chun Doo-hwan's visit. SK foreign minister and 20 others killed. One bomber confesses to being NK military.

Bomb explodes at Myanmar memorial during SK President Chun Doo-hwan's visit. SK foreign minister and 20 others killed. One bomber confesses to being NK military. 1987: Two suspected NK agents plant bomb on SK plane from Baghdad to Seoul. Bomb explodes after pair disembarks in Abu Dhabi — 115 people, mostly from SK, die.

Two suspected NK agents plant bomb on SK plane from Baghdad to Seoul. Bomb explodes after pair disembarks in Abu Dhabi — 115 people, mostly from SK, die. 1997: NK defector Lee Han-young, Kim Jong-nam's cousin, is shot and killed in SK by two people who were never caught. Suspected to be NK agents.

NK defector Lee Han-young, Kim Jong-nam's cousin, is shot and killed in SK by two people who were never caught. Suspected to be NK agents. 2010: SK authorities arrest two NK operatives the South say were on a mission to assassinate Hwang Jang-yop, a defector and former NK Workers' Party secretary.

SK authorities arrest two NK operatives the South say were on a mission to assassinate Hwang Jang-yop, a defector and former NK Workers' Party secretary. 2011: A NK agent was jailed in the South for attempting to assassinate Park Sang-hak, a NK defector, with a poison-tipped needle. Source: Reuters

Reuters/AP