NORTH KOREA has accused the US Central Intelligence Agency and South Korea's intelligence service of a failed plot to assassinate its leader Kim Jong Un with a biochemical bomb at a military parade in Pyongyang.

North Korea has a history of accusing the United States and South Korea of planning preemptive military attacks and to target its leaders, but analysts said it could be the first time it has accused the allies of an actual assassination attempt.

Pyongyang presented extensive details but offered no concrete proof to back its accusations of the plot, which it said could never have succeeded.

The CIA and the White House declined to comment on the statement from North Korea's Ministry of State Security, which accused the CIA and South Korea's National Intelligence Service of bribing a North Korean to target the country's "supreme leadership."

The charge came just after a visit to South Korea by CIA director Mike Pompeo and at a time of high tension driven by concerns that North Korea may conduct a sixth nuclear test or further missile launches in defiance of U.N. Security Council resolutions.

The North Korean statement, carried by the official Korean Central News Agency - which often issues shrill, bellicose threats and accusations against the United States and South Korea - said the foreign intelligence agencies "infiltrated" North Korea "to commit state-sponsored terrorism."

It said they had "ideologically corrupted" and bribed a North Korean surnamed Kim - the most common Korean surname - and turned him into "a terrorist full of repugnance and revenge against the supreme leadership."

"They hatched a plot of letting human scum Kim commit bomb terrorism targeting the supreme leadership during events at the Kumsusan Palace of the Sun and at military parade and public procession after his return home," KCNA said.

"They told him that assassination by use of biochemical substances, including radioactive substance and nano poisonous substance, is the best method that does not require access to the target, their lethal results will appear after six or twelve months," the statement said.

It said Kim received two payments of $20,000 and a "satellite transmitter-receiver."

KCNA claimed the assassin was a "lumberjack" who used to work in Russia

The statement did not make clear the timing of the alleged plot, but North Korea conducted an annual military parade in Pyongyang, featuring a display of missiles overseen by top leader Kim Jong Un and his right-hand men, on April 15.

The North Korean statement said the plan had "been put into the extremely serious phase of implementation."

Pyongyang has accused the United States and South Korea in the past of plots to assassinate its leadership. It has described regular U.S.-South Korea military exercises as plans to "decapitate" its leadership.

South Korea's Yonhap news agency quoted South Korea's Defense Minister Han Min Koo as saying on Jan. 4 that South Korea would launch a special unit this year tasked with "removing or paralyzing" North Korea's command structure in the event of a war.

North Korea warned this week that U.S. hostility had brought the region to the brink of nuclear war. It said the plot was a "last-ditch effort" by U.S. "imperialists" and South Korea that had gone "beyond the limits."

Bruce Klingner, a former CIA analyst now at the Heritage Foundation think tank, said it could be the first time North Korea had accused the allies of an attempted assassination.

He said North Korea's aim could be to divert attention from the use of VX nerve gas to assassinate the estranged half-brother of Kim Jong Un at Malaysia's Kuala Lumpur International Airport in February, or to influence South Korea's May 9 election.

The airport attack, blamed by the United States and Seoul on North Korean agents, has been cited by Washington in its efforts to persuade countries to minimize ties with North Korea.

"The regime may also be seeking to influence the upcoming South Korean presidential election in favor of progressive candidate Moon Jae-in by portraying rising tensions on the peninsula as the result of conservative governments in Washington and Seoul," Klingner said.

The Trump administration has said that all options, including military, remain on the table in dealing with North Korea, but that it is not pursuing a policy of regime change.

It has said its preferred route is to pressure North Korea to given up its nuclear and missile programs through sanctions.

U.S. Secretary of State Rex Tillerson said on Wednesday that Washington was working on more sanctions against North Korea if it takes steps that merit a new response.

Reuters