Seoul: North Korea said today it had formally entered a "state of war" with South Korea and warned that any provocation would swiftly escalate into a nuclear conflict.
"As of now, inter-Korea relations enter a state of war and all matters between the two Koreas will be handled according to wartime protocol," the North said in a statement attributed to all government bodies and institutions.
It is the latest in a string of dire threats from Pyongyang that have been matched by tough warnings from South Korea and the United States, fuelling international concerns that the situation is spiralling out of control.
"The long-standing situation of the Korean peninsula being neither at peace nor at war is finally over," said the statement carried by the official Korean Central News Agency (KCNA).
The two Koreas have always technically remained at war because the 1950-53 Korean War concluded with an armistice rather than a peace treaty.
The North had announced earlier this month that it was ripping up the armistice and other bilateral peace pacts signed with Seoul in protest against South Korea-US joint military exercises.
"This is not really a new threat - just part of a series of provocative threats," the South's Unification Ministry said
in a statement.
The defence ministry added that no particular troop movement had been observed along the border.
Voiding the ceasefire theoretically opened the way to a resumption of hostilities, although observers noted it was far from the first time that North Korea had announced the demise of the armistice.