North Korea is apparently preparing for a possible visit by outside inspectors to verify the shutdown of its nuclear test site in the northeast, Seoul's spy agency said Wednesday during a parliamentary audit.

After his fourth visit to North Korea in October, US Secretary of State Mike Pompeo said that North Korean leader Kim Jong-un had promised to let foreign inspectors visit the Punggye-ri site as soon as logistics-related details are worked out.

In May, the North demolished its nuclear test site before foreign journalists but without the presence of outside experts.

The North has conducted all six of its nuclear tests there, including the latest in September 2017.

At the closed-door audit session, the National Intelligence Service briefed lawmakers that it is closely monitoring the North's movement.

"Signs have been detected that North Korea is doing some preparations and intelligence-related activity over a possible visit by outside experts, as it shut down the nuclear test site and demolished some of the missile launching facilities at Dongchang-ri," the NIS was quoted as saying by Rep. Kim Min-ki of the ruling party.

The North's leader agreed to permanently shut down its Dongchang-ri missile engine testing facility and missile launch pad under the participation of outside experts during his Pyongyang summit with President Moon Jae-in in September.

The lawmaker said that the spy agency is closely monitoring North Korea's nuclear and missile facilities, including the Yongbyon nuclear complex, and no big changes have been detected.

The NIS also said that North Korea has continued to engage in hacking attacks to steal information and money, breaking into email accounts and mining virtual currency to earn foreign currency. (Yonhap)