North Korea live-fire drill and Kim Jong-un
North Korean leader Kim Jong-Un guides a firing contest among multiple launch rocket system (MLRS) batteries selected from large combined units of the KPA, in this undated photo KCNA via Reuters

North Korea has accused the CIA and South Korea of plotting to assassinate the country's leader, Kim Jong-Un, it has been reported.

A statement, carried by North Korean news agency KCNA, said the alleged plot included the use of "biochemical substances including radioactive substance and nano poisonous substance".

The supreme leader would have been targeted at a military parade and public procession, with the results not be visible for six to 12 months afterwards, KCNA reported.

It claimed that a terrorist group, back by South Korea and the CIA, had entered the country to attack with a bio-chemical substance.

This comes as a number of high-profile missile tests by North Korea has angered those in the region including the South, Japan and China.

Some tests have failed, but the rate of tests over the past month is at a record high.

The US has sent ships and engaged in military exercises along the Korea border.

More recently, US President Donald Trump has vowed to "properly deal" with North Korea as it continues to test ballistic missiles off the peninsular.

Kim visited military detachments on two islets controlled by North Korea on Friday (5 May), while forming a strategy against the "South Korean puppet army", state media reported.

"He said that the KPA elite artillery group defending the south-west front should keep highly alert to break the backbone of the enemy once ordered," a North Korean report claimed, following the activation of the American Thaad missile defence system and intensified joint military drills.

The US has approved tighter sanctions on the hermit nation which would impact on China, Pyongyang's most important trading partner.

Recent tests by North Korea have drawn international condemnation, with Beijing becoming increasingly frustrated itself at these test and have shown no opposition to increased sanctions.