North Korea has enriched enough uranium to build a double-digit number of nuclear bombs, according to Seouls spy agency.
South Koreas National Intelligence Service (NIS) claimed that North Korea is also making progress in its efforts to develop more powerful and accurate missiles to target the country.
A behind-closed-doors parliamentary briefing by the National Intelligence Service came after North Korea offered a rare glimpse into a secretive facility to produce weapons-grade uranium earlier this month.
This saw its leader Kim Jong Un reiterate his goal to exponentially increase his stock of nuclear weapons.
The NIS assessed that Mr Kims disclosure of the facility was probably a statement of defiance towards Washington ahead of the US presidential election.
North Korean leader Kim Jong Un attends a ceremony where the new super-large multiple rocker launchers were presented on January 1 2023
This photo provided by the North Korean government shows a test of weapon systems, in North Korea on Saturday May 4 2019
This image released by Maxar Technologies shows an overview of a processing facility at the Yongbyon Nuclear Research Facility complex in Yongbyon, North Korea, on September 14 2021
A TV screen shows an image of North Korean leader Kim Jong Un during a news program at the Seoul Railway Station in Seoul on Friday September 13. It reads: North Korea, unveiling the uranium enrichment facility for the first time.
It was also deemed by the organisation as a way of domestically showcasing his military accomplishments amid deepening economic struggles, according to Lee Seong-kweun, one of the legislators who attended the briefing.
Lee said that North Koreas bomb fuel capacity included an unspecified but considerable amount of weapons-grade uranium that would be enough to build at least a double-digit number of weapons.
The agency also said that North Korea has an estimated 70kg (154lbs) of plutonium.
North Korean state media did not disclose the location of the uranium enrichment facility that Mr Kim visited on September 13.
However, Park Sun-won, another legislator who attended the briefing, said it was likely to be a site in Kangson, near the North Korean capital Pyongyang.
Along with the Norths main nuclear complex in the town of Yongbyon, the Kangson plant is one of two known sites in North Korea that has been linked to uranium enrichment activities.
Some analysts say North Korea may have more hidden sites for enriching uranium.
Mr Kims visit to the uranium enrichment site was followed by a North Korean missile test days later, as the country continues to flaunt its weapons capabilities in the face of deepening confrontations with Washington and Seoul.
North Korean state media said the test launches on September 18 involved two types of new missiles.
North Korean leader Kim Jong Un looks on as a rocket carrying a spy satellite Malligyong-1 is launched in North Gyeongsang Province, North Korea on November 21 2023
One is said to be designed to deliver super-large conventional warheads while the other is a strategic cruise missile, implying that it was developed for nuclear strikes.
North Korean state media reports on the tests suggested that the country was improving the capabilities of the weapons.
They are designed for delivering precision strikes on South Korean targets, the legislators paraphrased the South Korean spy agency as saying.
Some analysts speculate that North Korea could attempt to dial up pressure on Washington by conducting a nuclear test ahead of the US presidential election.
However, the KIS assessed that North Korea could wait on a nuclear test until after the election since there are other steps it may want to try first.
These could be in the form of test-firing a long-range missile targeting the US mainland or launching a military reconnaissance satellite, Lee said.