SEOUL — South Korean security officials have arrested two North Korean spies for plotting to assassinate a high-ranking defector, a report said Tuesday.

The two people from the North's military espionage unit were detained by South Korean intelligence officials after arriving in Seoul with an order to kill Hwang Jang-Yop, Yonhap news agency said.

Hwang, the architect of the North Korean regime's ideology of "juche", or self-reliance, was once secretary of the ruling Workers' Party and a tutor to leader Kim Jong-Il.

He defected in 1997 during a visit to Beijing, becoming the highest-ranking official ever to flee the hardline communist state.

The 87-year-old now lives under guard at a secret address in South Korea to forestall any attempts by the North to assassinate him. He has received several death threats.

South Korean officials were not immediately reachable for comment.

Yonhap quoted prosecutors as saying the spies secretly entered Thailand last December through China, disguising themselves as defectors. They were later sent to South Korea.

The North Koreans, identified as Kim and Tong, both 36, had been trained as spies since 2004, it said.

The North's official Uriminzokkiri website issued a commentary on April 5 threatening Hwang with death over his criticism of Pyongyang's regime.

"You must not forget traitors have always been slaughtered with knives," it said.

The commentary, which followed trips by Hwang to the United States and Japan, described him as a "traitor and human scum" and said he had "viciously slandered our dignity and system" during his trips.

Copyright © 2010 AFP. All rights reserved.