South Korea's top spy agency said Friday that it will show the usage records of controversial hacking programs to lawmakers in coming days, a rare move to back up its claims that it has never used the programs to monitor civilians.

The National Intelligence Service said the usage records of the hacking software are classified, but it will allow lawmakers to see them as "an emergency measure."

"It will become clear that the NIS did not carry out surveillance of civilians once" the lawmakers see the records, the spy agency said in a statement. "There is no reason to lie."

The statement came amid lingering controversy over the hacking software programs the spy agency purchased from an Italian hacking firm in 2012.

The software program uses Remote Control System technology, which could allow hackers to manipulate and track smartphones and computers by installing spyware.

The NIS said it bought the programs that can be used to hack into up to 20 mobile phones simultaneously and said the programs are designed to work through the Italian company.

The spy agency said 97 agencies from 35 different countries have bought the hacking software programs from the Italian company, though no country is as mired in controversy as South Korea. It did not name the other 95 agencies.

"Why would the NIS carry out surveillance on our own people?" the statement asked.

Some South Koreans have lingering doubts about the spy agency as it had previously been accused of various illegal acts such as the wiretapping of politicians, journalists and others in the past.

The NIS has said that it used most of the programs for the purpose of strengthening cyber warfare capabilities against Pyongyang.

A ruling Saenuri Party official said 18 out of 20 hacking programs were used to try to glean intelligence on North Korea while the two others for research purposes. The official asked not to be identified, citing the issue's sensitivity. 

The spy agency said it is "the first line of defense" against a grim security situation, in an apparent reference to threats posed by North Korea's cyber attacks as well as its missile and nuclear programs.

South Korea was hit by a series of cyber attacks in recent years that were blamed on North Korea, though the North has denied any involvement. 

In April, South Korea said that North Korea is believed to be linked to a series of leaked data on South Korea's nuclear power plants in December. (Yonhap)