North Korea severed the inter-Korean communication hotline that runs through the truce village of Panmunjom following its threat to do so last week, South Korea's unification ministry said Monday.

The ministry said the North seems to have disconnected the emergency link set up to ensure prompt two-way communication to deal with any sudden developments along the demilitarized zone that separates the two Koreas. It said attempts to contact the North by telephone at 9 a.m. failed.

Pyongyang warned last week that it will no longer respect the armistice agreement that halted the Korean War (1950-53) as of Monday, and threatened to cut the communications hotline as well as pull out its military liaison office from Panmunjom.

North Korea also said that all non-aggression pacts reached in the past between Seoul and Pyongyang were null and void, and warned it can take military measures to counter provocations caused by the start of the annual South Korea-U.S. Key Resolve exercise.

Pyongyang in recent days stepped up its attack against the military exercise that is designed to repel any armed aggression from the North as a war game aimed at invading the North.

Inter-Korean tensions have been running high since the North detonated its third nuclear device on Feb. 12 and the United Nations agreed to slap tougher sanctions against the communist country for its provocations.

The North has repeatedly threatened to turn Seoul and Washington into a "sea of fire" and claimed it has the nuclear capability to harshly strike its foes. (Yonhap News)