Suh Hoon, chief of the National Intelligence Service, at the floor meeting of the National Assembly's Intelligence Committee on Tuesday. Yonhap

North Korea seems to be operating uranium enrichment facilities normally at the Yongbyon nuclear complex, South Korea's spy agency was quoted as saying by lawmakers.

"(North Korea's) uranium enrichment facilities were known to be in normal operation even before the recent summit between the leaders of between the United States and North Korea," Suh Hoon, chief of the National Intelligence Service (NIS), was quoted as telling lawmakers at the closed-door briefing Tuesday.

The spy agency said that North Korea stopped the operation of its 5-megawatt reactor at its sprawling nuclear complex in Yongbyon late last year with no signs of reprocessing activities.

At a press briefing Tuesday, lawmakers said the North has been keeping the nuclear reactor dormant, but they did not make public the North's uranium enrichment activities at Yongbyon.