North Korea has accused US and South Korean agents of plotting to kill its Supreme Leader, Kim Jong-un.
A North Korean referred to only as "Kim" was paid to carry out an attack with biochemical substances, the ministry of state security said.
The plot was foiled, it said, but gave no details on the fate of "Kim". The CIA declined to comment and South Korea has issued no statement so far.
The North's claim comes amid continued high tension on the Korean peninsula.
US President Donald Trump has promised to "solve" North Korea and stop it developing nuclear weapons.
An unconvincing case: Stephen Evans, BBC News, Seoul
The statement should be treated with scepticism. The regime has a track record of false information. It would be surprising if American or South Korean intelligence agencies didn't try to have agents in North Korea but the specific allegations about an assassination plot raise many questions.
Why hasn't a suspect been produced? Why does the KCNA statement cite poisoning at one moment and a bombing the next? How would anyone get access to Kim Jong-un, a man perpetually surrounded by squads of protectors and whose movements are secret?
Journalists who go to Pyongyang have cell-phones taken off them whenever they go to events where he might be, presumably to prevent tracking - so how would an ordinary citizen get more access?
Plots to kill Kim Jong-un may have been hatched but a bald statement by the media controlled by a vicious regime does not add up to convincing evidence.
The ministry of state security statement, carried by state news agency KCNA, said the CIA and South Korean intelligence services had "hatched a vicious plot to hurt the supreme leadership of the DPRK".
It did not mention Kim Jong-un by name, but he is widely referred to as the supreme leader.
The ministry said a plot had been hatched to use "bomb terrorism" to target the supreme leadership at a military parade or at an event at the Kumsusan Palace of the Sun, the mausoleum of Kim Il-sung, the country's founding leader.
It said "Kim" had been told that the best method was the use of "biochemical substances including radioactive substance and nano poisonous substance" whose results would "appear after six or 12 months".
Follow the link to see the source article published by The BBC May 5, 2017.