North Korea could have up to 60 nuclear weapons, Seoul has claimed, in its first public remarks about the size of the Pyongyang’s secret atomic arsenal.

South Korea’s unification minister, Cho Myoung-gyon, said that parliament intelligence authorities estimated North Korea had between 20 and 60 bombs.

Mr Cho may have unintentionally revealed the information. His ministry later said his comments didn’t 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 official’s words came hours after Seoul said their northern cousins had began removing mines from along their heavily armed border as part of recent steps to reduce tensions.

The effort is expected to only root out a small portion of the 2 million mines that litter the 248km-long, 4km-wide Demilitarised Zone that divides the nations.

Nevertheless, officials hailed the clearing work as “the start of peace” between the two nations, which are still technically at war following the 1950-53 Korean conflict.

South Korean estimates of the North’s arsenal are similar to various civilian estimates, which are largely based on calculations of the amount of nuclear materials the North is believed to have produced.

North Korea military parade celebrating nation's 70th anniversary Show all 18 1 /18 North Korea military parade celebrating nation's 70th anniversary North Korea military parade celebrating nation's 70th anniversary Participants wave flowers AFP/Getty North Korea military parade celebrating nation's 70th anniversary North Korea's leader Kim Jong Un (R) waves with China's Chairman of the Standing Committee of the National People's Congress Li Zhanshu (L) from a balcony AFP/Getty North Korea military parade celebrating nation's 70th anniversary Airplanes forming the number 70 fly in formation and fire flares AP North Korea military parade celebrating nation's 70th anniversary North Korean performers dance EPA North Korea military parade celebrating nation's 70th anniversary North Korean military officers applaud near portraits of late North Korean leaders Kim Il Sung and Kim Jong Il AP North Korea military parade celebrating nation's 70th anniversary North Korean tanks roll past AP North Korea military parade celebrating nation's 70th anniversary Participants cheer as they take part in a parade for the 70th anniversary of North Korea's founding day in Pyongyang, North Korea, Sunday, Sept. 9, 2018. North Korea staged a major military parade, huge rallies and will revive its iconic mass games on Sunday to mark its 70th anniversary as a nation. (AP Photo/Ng Han Guan) Ng Han Guan AP North Korea military parade celebrating nation's 70th anniversary Korean People's Army (KPA) soldiers take part AFP/Getty North Korea military parade celebrating nation's 70th anniversary Korean People's Army (KPA) soldiers march AFP/Getty North Korea military parade celebrating nation's 70th anniversary Participants march during a mass rally on Kim Il Sung square in Pyongyang AFP/Getty North Korea military parade celebrating nation's 70th anniversary A girl reacts during a parade AP North Korea military parade celebrating nation's 70th anniversary North Korean leader Kim Jong Un, right, reacts as he chats with China's third highest ranking official, Li Zhanshu AP North Korea military parade celebrating nation's 70th anniversary People carry flags in front of statues of North Korea founder Kim Il Sung (L) and late leader Kim Jong Il Reuters North Korea military parade celebrating nation's 70th anniversary Performers take part in a concert at the Pyongyang Indoor Stadium AFP/Getty North Korea military parade celebrating nation's 70th anniversary North Korean artillery roll past AP North Korea military parade celebrating nation's 70th anniversary Students perform Reuters North Korea military parade celebrating nation's 70th anniversary Soldiers march during a military parade Reuters North Korea military parade celebrating nation's 70th anniversary Participants wave flowers AFP/Getty

Stanford University scholars wrote earlier this year that North Korea is estimated to possess from 250 to 500 kilograms of highly enriched uranium, enough for 25 to 30 nuclear devices.