Seoul, Feb 15 (IANS): The chief of South Korea's spy agency on Wednesday confirmed that North Korean leader Kim Jong-un's half-brother was murdered with poison in Malaysia.

National Intelligence Service (NIS) Director Lee Byong-ho told lawmakers that for the past five years Pyongyang has been attempting to assassinate Kim Jong-nam, who was under the protection of the Chinese government, Yonhap reported.

During a meeting with the National Assembly's Intelligence Committee, Lee confirmed that Kim was killed with poison at the airport, although it still needs to find out whether a needle or chemical spray was used.

The agency conceded it was notified of the incident about four hours after it occurred.

Kim was at the airport to take an airplane heading to Macao when he asked the staff for help after interacting with two "Asian" women. Kim died on the way to a nearby hospital.

The Malaysian authorities presume Kim was poisoned, although details will be revealed only through an autopsy. The agency said the suspects are presumed to be still at large in Malaysia.

"There was also an (assassination attempt) in 2012," Lee was quoted as saying by Rep. Kim Byung-kee of the Democratic Party. Lee said the North's latest action is presumed to have been based on Kim Jong-un's "delusional disorder," rather than on any calculation that his half-brother is a threat to the regime.

The NIS head also told lawmakers that Kim sent a letter to the North Korean leader Kim Jong-un in 2012, asking his brother to spare his and his family's lives.

Kim Jong-nam's wife is currently staying in Beijing with a son, while his second wife is living in Macao with a son and a daughter. All of them are currently under the protection of Chinese authorities.

The agency said Kim had never asked South Korea for asylum, nor was there an effort within North Korea to place Kim Jong-nam as the leader.

South Korea's Unification Ministry also said it was certain that Kim has been killed in Malaysia.

"Police in Malaysia are conducting a probe into the killing, and they have yet to announce the results (of the investigation)," Jeong Joon-hee, spokesman at Seoul's Unification Ministry said. "Seoul is closely cooperating with the Malaysian government."

Experts said that Kim might have been killed due to the North Korean leader's move to strengthen his reign of terror by eliminating any potential rivals to his iron-fist rule.

Kim Jong-nam -- the eldest son of late former leader Kim Jong-Il -- had been living in foreign countries for years after apparently falling out of favour with his father for attempting to enter Japan on a fake passport in 2001.

He was critical of the power succession to his brother Kim Jong-un.