North Korea has accused the United States of trying to influence voters in next month's presidential election by scaring them with reports of North Korean submarine incursions into South Korean waters.
Earlier this month, South Korea launched exhaustive but fruitless search-and-destroy missions around its coast after what South Korean media reports said was a U.S. military tip-off about two North Korean submarines.
"We would like to clarify that this case itself is a fabrication and a far-fetched assertion to serve the purpose of the anti-DPRK scenario worked out by the U.S.," the North's official KCNA news agency quoted a North Korean military spokesman as saying late on Saturday.
DPRK is short for the North's official name, the Democratic People's Republic of Korea.
"Through this, the present ruling quarters in the U.S. sought to hype up the fiction of possible provocation from the DPRK in a bid to influence American voters in the run-up to the presidential election there," the spokesman said.
The spokesman said the submarine report had also been intended to dramatise North Korea's failure to return for a fourth round of scheduled talks in September on its nuclear programmes.
Seoul's defence ministry and the United States Forces Korea declined to comment on Pyongyang's accusation.
South Korea takes seriously any reported sightings of North Korean submarines or other naval vessels in or near its waters.
In September 1996, a North Korean submarine ran aground off South Korea's east coast with two dozen North Korean agents on board.
South and North Korea are technically at war because the 1950-53 Korean War ended in a truce rather than a peace treaty.
Despite economic rapprochement since a North-South summit in 2000, military tensions remain high on the divided peninsula, not least because of the North's declared nuclear ambitions.
On Saturday, North Korea threatened to double the size of its nuclear deterrent if the United States did not drop what Pyongyang sees as a confrontational policy aimed at unseating its communist leadership.