North Korea has accused the CIA and South Korea of a plot to assassinate Kim Jong-un with “biochemical substances”.

A statement from the ministry of state security claimed “hotbeds of evils in the world hatched a vicious plot” targeting Mr Kim during a public appearance for ceremonial events in Pyongyang.

It said a terrorist group backed by the CIA and South Korean spies had entered the country for the attempted assassination, vowing that an “anti-terrorist attack” would begin immediately.

The statement threatened that the “the last-ditch effort” of American “imperialists” and the South had gone “beyond the limits”.

“A hideous terrorists’ group, which the CIA and the National Intelligence Service infiltrated into the DPRK on the basis of covert and meticulous preparations to commit state-sponsored terrorism against the supreme leadership of the DPRK by use of biochemical substance, has been recently detected,” it continued.

It claimed the two intelligence agencies “ideologically corrupted” and bribed a North Korean with the surname Kim, turning him into “a terrorist full of repugnance and revenge against the supreme leadership of the DPRK”.

North Korea shows new missiles in huge parade amid nuclear fears

“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,” the Korean Central News Agency (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.

“Then they handed him over $20,000 (£16,000) on two occasions and a satellite transmitter-receiver and let him get versed in it.”

KCNA, which frequently carries threats from the North Korean government, gave lengthy details about the alleged plot but claimed it could not be accomplished.

“Criminals going hell-bent to realise such a pipe dream cannot survive on this land even a moment,” it said.

In pictures: North Korea military drill Show all 8 1 /8 In pictures: North Korea military drill In pictures: North Korea military drill North Korea's leader Kim Jong Un watches a military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) is seen in this handout photo by North Korea's Korean Central News Agency (KCNA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) is seen in this handout photo by North Korea's Korean Central News Agency (KCNA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) KCNA/Handout via REUTERS In pictures: North Korea military drill A military drill marking the 85th anniversary of the establishment of the Korean People's Army (KPA) KCNA/Handout via REUTERS In pictures: North Korea military drill This image made from video of still images broadcast in a news bulletin by North Korea's KRT, shows what was said to be a 'Combined Fire Demonstration' held to celebrate the 85th anniversary of the North Korean army, in Wonsan, North Korea. KRT via AP Video In pictures: North Korea military drill This image made from video of still images broadcast in a news bulletin by North Korea's KRT, shows what was said to be a 'Combined Fire Demonstration' held to celebrate the 85th anniversary of the North Korean army, in Wonsan, North Korea. KRT via AP Video In pictures: North Korea military drill This image made from video of still images broadcast in a news bulletin by North Korea's KRT, shows what was said to be a 'Combined Fire Demonstration' held to celebrate the 85th anniversary of the North Korean army, in Wonsan, North Korea. KRT via AP Video

The leader’s estranged half-brother, Kim Jong-nam, was assassinated using VX nerve agent at Kuala Lumpur International Airport earlier this year.

The latest allegations emerged amid heightened tensions over a series of weapons tests carried out by the totalitarian state.

US President Donald Trump has vowed to “properly deal” with Pyongyang, raising fears of a preemptive strike that could provoke a nuclear response.

Mr Kim visited military detachments on two islets controlled by North Korea, while forming a strategy against the “South Korean puppet army”, state media reported on Friday.

“He said that the KPA elite artillery group defending the southwest front should keep highly alert to break the backbone of the enemy once ordered,” a KCNA report claimed, following the activation of the American Terminal High-Altitude Area Defence, or Thaad, missile defence system and intensified joint military drills.

During a visit to Jangjae and Mu islands, Mr Kim reportedly “acquainted and examined the plan for fire strike of the newly organised forces at the objects of the enemy”.

He toured facilities including barracks and a desalination plant, while “taking warm care” of soldiers and being photographed with their families.

North Korea test-fires an underwater strategic submarine ballistic missile (EPA)

North Korea has stationed multiple rocket launchers and artillery units on the two islands, where a shelling and rocket attack was launched on South Korea’s Yeonpyeong Island in 2010.

Rex Tillerson, the US Secretary of State, said Washington was working on fresh sanctions against North Korea if it takes steps that merit a new response, and warned other countries would be punished for doing illicit business with Pyongyang.

The US House of Representatives has overwhelmingly approved legislation to tighten sanctions on North Korea by targeting its shipping industry and companies that do business with the reclusive state.

Supporters hoped it would send a strong message to North Korea, amid international concern over the escalation of its nuclear programme.

If the sanctions are approved by the Senate and become law, they are likely to affect China, Pyongyang’s most important trade partner.

Beijing has been angered by North Korea’s nuclear and missile tests and supported US sanctions, but foreign ministry spokesperson Geng Shuang said it opposes other countries using their own domestic law to impose unilateral sanctions.

He urged all sides to exercise restraint and not irritate each other to avoid the situation worsening.