The Democratic People's Republic of Korea (DPRK) has reportedly severed an inter-Korean communication hotline following its threat to do so last week, the unification ministry said here Monday.

The ministry said the DPRK seems to have cut the emergency link set up to deal with any contingency along the demilitarized zone of Panmunjom, which separates the two Koreas, Yonhap News Agency reported.

South Korea and the United States began "Key Resolve" joint military exercises on Monday, which is scheduled to run through March 21, despite DPRK's warning of annulment of the armistice agreement that halted the Korean War (1950-53).

Tensions have been running high since DPRK conducted its third nuclear test on Feb. 12, and the United Nations agreed to impose tougher sanctions on the country for its renewed provocations.