Wiretapping of phones alerted South Korean intelligence services that North Korean eminence grise Jang Song-taek had been ousted, a government official said Wednesday.
The official said intelligence services garnered "credible intelligence supporting the rumors through wiretaps." They then cross-checked the information with reliable sources.
Democratic Party lawmaker Hong Ik-pyo said the first information the National Intelligence Service obtained on Nov. 18 was that Jang had been put under house arrest after his closest confidants Ri Yong-ha and Jang Su-gil were arrested and later publicly executed.
But Hong cited intelligence data as showing that plans to further open North Korea's special economic zones in Sinuiju, Nampo and Wonsan, which were spearheaded by Jang, would continue.
Free North Korea Radio, which is run by defectors, cited sources in Pyongyang as saying Jang was arrested by military intelligence on Nov. 30 amid a heightened alert for the military. Officers were told to arrest Jang before he could try to mobilize support in the state security apparatus, where he wielded some influence.
The source said North Korean leader Kim Jong-un personally ordered the purge to punish Jang for "arrogance" and had agents tap the phones of his confidants. "This led to the public execution of Ri and Ha on Nov. 12," the source added.
But that account conflicts with the government's version that the two were executed in late November.