U.S. and South Korean war games on the divided peninsula have the effect of holding a gun to North Korea's head and could hamper efforts to negotiate an end to its nuclear weapons development, Pyongyang said.

Although U.S.-South Korean joint training drills have gone ahead for decades without major incident, North Korea typically reserves some of its harshest language to denounce them, casting them as a prelude to an invasion and nuclear war.

"The projected provocative saber-rattling is an uncouth act little short of leveling a gun at the dialogue partner," said a spokesman for Pyongyang's unification committee, quoted by the North's official KCNA news agency late on Saturday.

The rival Korean states are still technically at war having never signed a formal peace treaty to end their 1950-1953 conflict. A supposedly temporary armistice still holds after more than half a century, freezing the nation's division.

The U.S. military, which continues to station some 30,000 troops in South Korea under a long-standing defense pact, has scheduled this year's annual training exercises with South Korea from March 25 to 31. It informed the North's army of the drills and reassured Pyongyang they were not meant to be provocative.

Officially the North was unimpressed. "The war moves will only becloud the prospect for the settlement of the nuclear issue on the Korean peninsula and bring destruction," the unification committee spokesman said.

Reclusive, impoverished North Korea agreed last month to take initial steps toward scrapping its nuclear arms program by saying it would shut its main reactor, the source of its weapons-grade plutonium, in exchange for energy aid.

Later this month, North Korea is slated to join China, Japan, Russia, South Korea and the United States in Beijing to resume discussions on permanently ending its nuclear weapons program in exchange for aid and better diplomatic ties.

The joint military training, dubbed RSOI Foal Eagle, involve about 29,000 U.S. troops and an undisclosed number of South Korean troops, a U.S Forces Korea spokesman said.

He said some 6,000 U.S. troops stationed outside the peninsula would take part in the drills, along with a U.S. aircraft carrier group.

North Korea has a 1.2 million-strong standing military, most of whom are stationed near the heavily fortified border.