North Korea claims US tried to assassinate Kim Jong-un

North Korea has accused US agents of masterminding an attempt to assassinate Kim Jong-un using a biological weapon.

The country's Ministry of State Security claimed that CIA agents worked with South Korean spies to recruit an "ideologically corrupted and bribed" North Korean citizen to carry out the plot.

He was to be given a bio-chemical weapon such as a delayed-action radioactive or "nano-poisonous" substance which was to be used on Mr Kim at a public appearance, according to the reports.

The ministry said the citizen had been recruited while working in Russia in June 2014 and received a series of payments in return for his cooperation, according to reports in state media.

Western spy agents contacted the man just a month ago to say the CIA had decided on which poison to use, it was claimed.

North Korea has been building up its military and undertaking missile tests. Credit: AP

North Korean officials said they were beginning an "anti-terrorist attack" that would "sweep away the intelligence and plot-breeding organisations of the US imperialists and the puppet clique" after the alleged plot was uncovered.

North Korea frequently accuses the United States and South Korea of plotting against it, but this accusation is unusual in its detail.

It comes after Mr Kim's estranged half-brother Kim Jong-nam was killed at a Malaysian airport after he was sprayed with a deadly nerve agent.

Recent months have seen growing tension between North Korea and the US largely spurred by the rogue state's continued work on developing a nuclear and missile programme despite international sanctions.