South Korea's foreign ministry said Tuesday that an Armistice Agreement that ended the 1950-53 Korean War remains valid, despite the North's threats to scrap the cease-fire deal.

"The terms of the Armistice Agreement cannot be unilaterally invalid or terminated," foreign ministry spokesman Cho Tai-young said, demanding North Korea withdraw the threats.

North Korea said early this week that the armistice was "completely invalid," in response to tougher U.N. sanctions against the North's third nuclear test and ongoing joint military drills between Seoul and Washington.

Pyongyang had previously declared the armistice was invalid, but the North's increasingly menacing rhetoric following the U.N.

vote raised concerns that the isolated regime may stage another round of provocations.

Cho said South Korea will "strengthen coordination and cooperation with the U.S. and China, and sternly deal with any attempt from North Korea to scrap the Armistice Agreement." (Yonhap News)