North Korea may have reprocessed spent nuclear fuel rods at the Yongbyon Nuclear Complex this year, the South Korean spy agency was quoted as saying Thursday.

The National Intelligence Service confirmed the activity in a closed-door briefing at the parliamentary audit, Rep. Kim Byung-kee of the ruling Democratic Party of Korea said during a press briefing.

The spy agency said Pyongyang may have reprocessed spent fuel from its main 5MW(e) nuclear reactor in Yongbyon from February to July this year. By reprocessing spent fuel at the Yongbyon nuclear complex, which it shut down in early December 2018, the North can produce plutonium for weapons.

The agency’s assessment is consistent with the most recent annual report from the International Atomic Energy Agency.

In August, the IAEA said Pyongyang had restarted operations at Yongbyon in early July this year. The UN nuclear watchdog cited the discharge of cooling water as an indication the reactor was operating, and said it was the first sign of activity detected since December 2018.

The IAEA also said North Korea’s latest activity is likely to involve the reprocessing of spent nuclear fuel rods.

The nuclear watchdog pointed to indications that a nearby radiochemical laboratory was operating from mid-February to early July this year. The laboratory is used to extract plutonium by reprocessing spent fuel rods from the reactor for use in nuclear weapons.

This five-month period is longer than the usual time needed for waste treatment or maintenance activities, and is consistent with the duration of previous reprocessing campaigns, according to IAEA.

Meanwhile, the NIS brushed off rumors about North Korean leader Kim Jong-un’s health. According to the NIS, Kim appears have no health issues although he has lost around 20 kilograms, having previously weighed about 140 kilograms.

The spy agency also repudiated a rumor about the North Korean regime using an actor to stand in for the North Korean leader, dismissing it as “groundless and untrue.”

The NIS has been monitoring Kim’s health through detailed study with various scientific techniques, including artificial intelligence and ultra-high-resolution images that are sensitive enough to detect skin problems on his face.

The spy agency also said the North Korean leader has removed portraits of his late father and grandfather -- Kim Jong-il and Kim Il-sung, the country’s founder -- from the backdrop of official meetings.