Seoul - North Korea threatened Wednesday to close its borders with South Korea starting December 1, accusing Seoul of pursuing a confrontational policy against its neighbour.

North Korea would "strictly restrict and cut off all the overland passages" at the inter-Korean border, said a statement distributed by the country's official Korean Central News Agency.

"The South Korean puppet authorities should never forget that the present inter-Korean relations are at the crucial crossroads of existence and total severance," Pyongyang warned.

South Korea's military was informed of the decision, which is expected to put a further dampener on the already frosty bilateral relationship, in a telephone message, South Korea's Yonhap News Agency said.

The North Korean army said the "actual crucial measure" was taken in retaliation for the South's failure to abide by existing agreements made at summits in June 2000 and October 2007.

"The South Korean authorities are getting frantic in their racket for confrontation with the DPRK while paying lip-service to respect for the June 15 joint declaration and the October 4 declaration ... and resumption of dialogue for implementing them," the North Korean military's message said, referring to North Korea by the acronym of its official name, the Democratic People's Republic of Korea.

In 2000, the leaders of North and South Korea held their first summit, issuing a declaration on eventual peaceful reunification, confidence-building measures and economic cooperation. In 2007, a second declaration was signed to establish a permanent peace mechanism.

The two countries remain officially at war after the 1950-53 Korean War, which ended with a truce and not a peace treaty.

"The South Korean authorities' unchanged stand and attitude toward the historic two declarations have been finally confirmed," the North Korean statement said. "... The racket of confrontation with the DPRK kicked up by the South Korean authorities, including the military in particular, is going beyond the danger level despite its repeated warnings."

The communist state has recently stepped up verbal attacks against the South, repeatedly threatening to cut all ties. Relationships between the two Koreas have cooled markedly since a conservative government took office in Seoul in February.

Relations took a further dip as Pyongyang accused Seoul of not preventing South Korean activists from releasing balloons carrying propaganda leaflets near the border.

A full border shutdown would also affect cooperation projects like an industrial park just over the border near the North Koran city Kaesong and tourism, both important sources of income for the impoverished North.

Under South Korea's two previous administrations the two Koreas agreed to allow visits by families separated by the Korean War and inter-Korean border, hold ministerial and military talks, establish a joint industrial park, allow South Korean tourists to visit designated areas in the North and open regular rail service over the border, which began in December.