SEOUL, April 15, 2026 (BSS/AFP) - North Korea is showing a "very serious increase" in its ability to produce nuclear weapons, the head of the International Atomic Energy Agency (IAEA) said on Wednesday.

The diplomatically isolated nation is believed to operate multiple facilities for enriching uranium, a key step in making nuclear warheads, South Korea's spy agency has said.

They include one at the Yongbyon nuclear site, which Pyongyang purportedly decommissioned after talks but later reactivated in 2021.

"In our periodic assessments, we have been able to confirm that there's a rapid increase in the operations" of the Yongbyon reactor, IAEA chief Rafael Grossi said at a news conference in Seoul on Wednesday.

The agency had also observed a rise in operations at Yongbyon's reprocessing unit and light-water reactor, as well as the activation of other facilities, Grossi said.

"All that points to a very serious increase in the capabilities of (the) DPRK in the area of nuclear weapons production, which is estimated at a few dozen warheads," he said, referring to North Korea by its official name.

North Korea, which conducted its first nuclear test in 2006, is under rafts of UN sanctions for its banned weapons programmes.

It has declared that it will never surrender its nuclear weapons.

Asked whether Russia was assisting North Korea's nuclear development, Grossi said the IAEA had not seen "anything in particular in that regard".

North Korea