John Kerry slams Kim Jong-un's 'grotesque, grisly, horrendous executions' in North Korea

Defence minister Hyon Yong Chol was reportedly the latest to be killed

North Korean leader Kim Jong-un reportedly ordered the execution of his defence minister for treason (Reuters )

John Kerry has condemned North Korea’s “grotesque, grisly, horrendous public displays of executions” after Kim Jong-un reportedly ordered the death of his defence minister.

Hyon Yong Chol was publicly killed using an anti-aircraft gun, South Korean intelligence agents claimed, after being charged with treason.

He had allegedly voiced complaints about the young dictator, talked back to him and fallen asleep during a meeting Kim presided over.

Analysts have said Hyon's reported disobedience could be a sign of Kim's regime weakening and executions may not help.

Bill Richardson, the former governor of New Mexico who has visited North Korea several times as a negotiator, told CNN: “I think it shows some instability in Kim Jong-Un's regime that he's being challenged, that he's got serious opposition especially within the military.

"I think he's putting himself in a situation that he's not only going to be challenged again and again, but that he's going to create some internal opposition that in the end could topple him."

The US Secretary of State spoke about the latest reported execution in the secretive state while discussing imposing further nuclear sanctions.

North Korea is “not even close” to taking sufficient steps to reduce its nuclear weapons programme in line with international guidelines, he said today.

At a conference with the South Korean foreign minister in Seoul, Mr Kerry said Pyongyang had broken promises, made threats and shown a "flagrant disregard for international law" by continuing nuclear bomb and missile development.

"They have grown the threat of their programme and have acted with a kind of reckless abandon," he added.

North Korea conducted its first nuclear test in 2006 and is now believed to have at least 10 such weapons.

The country walked away from proposed agreement with China, Japan, Russia, South Korea and the United States to end its nuclear programme in return for diplomatic and economic rewards in 2005 and remains under heavy sanctions.

"I think never has the international community been as united as we are now, that, number one North Korea needs to denuclearise," Mr Kerry said, adding that a hoped-for nuclear deal with Iran could serve as an example.

Hyon was reportedly executed using an anti-aircraft gun (Getty)

He will be discussing sanctions and other measures with China, one of the only countries enjoying a diplomatic relationship with North Korea, in June.

North Korea is still technically at war with the South since the countries separated after a civil war in the 1950s.

The recently testing of what Pyongyang said was a submarine-launched ballistic missile raised regional tensions further.

Mr Kerry claimed it was likely that the North would be referred to the International Criminal Court for its numerous alleged human rights violations including prison camps, starvation, torture, rape and forced labour.

A satellite image of Camp 16, believed to be the largest North Korean gulag (Amnesty International)

"(Kim's) leadership is one of the most egregious examples of reckless disregard for human rights and human beings anywhere on the planet," Mr Kerry said, claiming "grotesque, grisly, horrendous public displays of executions" were orchestrated "on a whim and a fancy by the leader".

The UN General Assembly has recommended that the North be referred to the tribunal for crimes against humanity after an inquiry detailed “unspeakable atrocities” last year but diplomats from Pyongyang stormed out of a meeting addressing human rights in New York last month.

One North Korean representative had claimed police killings in Baltimore and Ferguson were proof that the US “is the true kingpin of human rights violations."

Additional reporting by agencies