A report has claimed that North Korea has begun testing the loading of the highly infectious killer bacteria anthrax on to intercontinental ballistic missiles.

A report in the Japanese newspaper Ashai on Tuesday (19 December) said that the hermit nation was testing the means of loading the biological weapon on to missiles that could reach South Korea, Japan and the United States.

Testing was being undertaken to ensure that the infection could survive the high temperatures of a missile launch, the report said.

The claims followed the US National Security Strategy report that North Korea, "a country that starves its own people, has spent hundreds of millions of dollars on nuclear, chemical, and biological weapons that could threaten our homeland".

According to experts in South Korea, the North has between 2,500 and 5,000 tonnes of chemical weapons stockpiled. Doubt remains whether it has the technology or skills required to weaponise the chemicals.

But Hamish de Bretton-Gordon, a former commanding officer of the British Armed Forces Joint Chemical Biological Radiological Nuclear (CBRN) Regiment, told IBTimes UK that although the weaponisation of anthrax would require skill and knowledge it would be entirely plausible that the North could carry out such an attack.

North Korea claims that it now has a functioning nuclear arsenal after its most recent missile test launch in November which saw the launch of a Hwasong-15 ICBM.

The missile is estimated to have been the largest fired by the Kim regime yet and had the potential to fly around 8,000 miles - enough to reach the US mainland.

But while concern has been raised about the possible use of anthrax, Bretton-Gordon said that the use of the VX nerve agent was even more worrying.

"Of more concern is the prospect of the very deadly nerve agent VX being loaded into one of their ICBMs. Five hundred kilograms in a warhead could kill thousands," he explained.

He noted that the regime had used VX to kill Kim's estranged half-brother, Kim Jong-nam, in Malaysia in February. A single pin drop of the substance can kill.

It is believed that North Korea has around 5,000 tonnes of VX and even if a missile launch failed, Bretton-Gordon warned that half of the chemicals on board would still reach the ground.

Fresh UN sanctions and ongoing missile tests have ratcheted up already high tensions between North Korea and the US.

Over the summer, Donald Trump threatened the hermit nation with "fire and fury" if they continued their nuclear missile developments.

This prompted angry responses from Pyongyang including the state-run newspaper calling for the Trump to face the death sentence.