A South Korean minister told lawmakers that North Korea is estimated to have up to 60 nuclear weapons, in Seoul’s first public comment about the size of the North’s secrecy-clouded weapons arsenal.

Unification Minister Cho Myoung-gyon told parliament on Monday the estimates on the size of North Korea’s nuclear arsenal range from 20 bombs to as many as 60. He was responding to a question by a lawmaker, saying the information came from the intelligence authorities. The National Intelligence Service, South Korea’s main spy agency, could not immediately comment.

Pyongyang shuns the end of Korean war as bargaining chip for its denuclearisation

Cho may have unintentionally revealed the information. His ministry said on Tuesday that Cho’s comments did not mean that South Korea would accept North Korea as a nuclear state, suggesting Seoul’s diplomatic efforts to rid the North of its nuclear programme would continue.

The South Korean assessment on the North’s arsenal is not much different from various outside civilian estimates largely based on the amount of nuclear materials that North is believed to have produced.

According to South Korean government reports, North is believed to have produced 50 kilograms (110 pounds) of weaponized plutonium, enough for at least eight bombs, as North can make one warhead with 8 kilograms (18 pounds) of plutonium or less. Stanford University scholars, including nuclear physicist Siegfried Hecker who visited North Korea’s centrifuge facility at Yongbyon in 2010, wrote earlier this year that North Korea is estimated to have a highly enriched uranium inventory of 250 to 500 kilograms (550 to 1,100 pounds), sufficient for 25 to 30 nuclear devices.

How to break the stalemate on the Korean peninsula as North and South Korea take centre-stage

Many foreign analysts say North Korea is probably running additional secret uranium-enrichment plants.