Seoul - A South Korean activist Friday admitted to espionage activities uncovered by Pyongyang, but rejected accusations of a plot to murder North Korean leader Kim Jong Il, a news report said.

Choi Sung-yong, head of the Family Assembly Abducted to North Korea, a South Korean NGO, said a North Korean man arrested by the North's State Security Agency on Thursday had been hired by him to gather information on the Communist state the Yonhap news agency reported.

Pyongyang had claimed the arrested man, whose name was given as Ri, had been hired by the South Koren intelligence service to "harm our leadership." South Korean officials denied any involvement.

"It has nothing to do with the South Korean intelligence agency, but the incident itself is mostly true," Choi was quoted as saying by Yonhap.

"I had engaged in those things or knew of them through my informants. The North's State Security Agency was announcing the result of its investigations spanning several years," Choi said.

He denied any attempts to plot the assassination of Kim Jong Il.

North Korea also said it arrested other spies, who were collecting environment samples to determine the level of the country's nuclear activity. (dpa)