SEOUL - North Korea complained on Monday that the South was engaging in psychological warfare along their heavily militarised border and warned of unpredictable results including "loss of human lives".

A statement issued by the North's official news agency referred to visits by media organisations and "other riff-raffs" close to the border aimed at preparing "anti-North smear campaigns" and urged the United States -- the South's ally -- to intervene.

"These days witness a lot of serious developments in the area along the Military Demarcation Line, where huge armed forces are standing in acute confrontation.... They may drive the present touch-and-go situation to a more dangerous phase," the agency said.

The statement made no mention of the countries' sea border, near to which a South Korean naval ship sank on Friday due to a mystery explosion.

South Korean officials have not so far suggested Pyongyang was involved in the incident, as a search continues for 46 missing sailors.

Tensions periodically flare along the land border. South Korean activists have regularly tried to send campaign materials, radios and, most recently, satellite telephones over the border as a means to helping undermine the Pyongyang government.

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