North Korea has called for an end to military hostilities with South Korea in an "open letter" sent to South Korean authorities.

"What is important for paving a wide avenue for mending North-South relations is to make a bold decision to stop all hostile military acts, the biggest hurdle stoking distrust and confrontation," the letter from Pyongyang's National Defence Commission (NDC) said.

The NDC had last week sent a series of proposals urging South Korea to cancel scheduled joint military exercises with the United States and proposing a mutual moratorium on provocative military actions and vilifying each other.

Seoul dismissed the requests as a "deceptive" propaganda exercise, and warned that Pyongyang may well be laying the ground for a provocative act aimed at triggering a confrontation.

"Regretfully, the South Korean authorities still remain unchanged in its improper attitude and negative stand," the NDC letter said.

The South "should not thoughtlessly doubt, misinterpret and rashly reject our sincere, important proposal," it added.

In its letter, the NDC stressed that its opposition lay solely in the participation of US forces in the exercises.

North Korea "did not urge the South Korean authorities to stop ordinary military drills," the letter said.

"It urged them to halt drills for a war of aggression to be staged against their compatriots in collusion with outside forces."

The NDC said it had also taken the "unilateral" step of halting all cross-border "slandering", despite the South's dismissive response to its proposal.

South Korea's Unification Ministry said the only "slander" was propagated by Pyongyang's propaganda machine.

Tensions on the Korean peninsula traditionally rise ahead of the annual South Korean-US drills, which Pyongyang condemn as a provocative rehearsal for invasion.

Last year's exercises were held following North Korea's third and largest nuclear test, which prompted months of escalated military tensions that saw Pyongyang issue threats of nuclear war against Seoul and Washington.

North-South Korean ties are currently in a state of watchful limbo, with both sides voicing willingness to improve relations while accusing the other of lacking sincerity.

Earlier this month, South Korean president Park Geun-Hye had called for the resumption of reunions for families separated by the Korean War.

But the North rejected the proposal, citing the South-US exercises as a major barrier.

AFP