North Korea declared all military and political agreements with South Korea over on Friday, warning it would not honour past accords if Seoul continues to push the countries to the brink of war.

The North's Committee for the Peaceful Reunification of Korea accused South Korean President Lee Myung-bak of raising tensions on the Korean peninsula with his hard-line position on Pyongyang. It warned that Lee's stance would only draw "a heavier blow and shameful destruction."

"The group of traitors has already reduced all the agreements reached between the North and the South in the past to dead documents," the committee, in charge of inter-Korean affairs, said early Friday in a statement carried by the state-run Korean Central News Agency.

Tensions between the two Koreas, which fought a bitter three-year war in the 1950s and remain divided by one of the world's most heavily armed borders, have been high since Lee took office in Seoul nearly a year ago.

Border should be pushed south, North Korea says

Lee, a conservative, pledged to get tough with Pyongyang, questioning the wisdom of his predecessors' "sunshine policy" of nurturing reconciliation by handing over unconditional aid to the nuclear-armed North. Pyongyang responded to Lee by cutting off all reconciliation talks with Seoul and ratcheting up the rhetoric.

Earlier this month, the North's military accused the South of preparing to wage war and said it was prepared to respond to any southern aggression.

Friday's statement specifically mentioned the Koreas' western maritime border, unilaterally drawn by the U.S.-led United Nations Command at the end of the 1950-53 Korean War.

Pyongyang claims the sea border should be redrawn farther south and on Friday declared agreements drawing the boundary "nullified."

Disputes over the border broke out in deadly skirmishes in 1999 and 2002.

In Seoul, Unification Ministry spokesman Kim Ho-nyeon said the government was studying the North's statement.