Elite North Korean soldiers are being armed with “nuclear backpacks”, a source has claimed as tensions increase over the authoritarian state’s attempts at military escalation.

An anonymous source told Radio Free Asia special units have been formed since March to carry the weapons and had been taking part in simulated training exercises with dummy bombs.

“Outstanding soldiers were selected from each reconnaissance platoon and light infantry brigade to form the nuclear backpack unit the size of a battalion,” the source from North Hamgyong province was quoted as saying.

The supposed weapons were said to weigh between 10 and 30 kilograms and be able to “spray radioactive material”, possibly uranium, on the enemy.

North Korea weapon tests

It was impossible to verify the account given to Radio Free Asia, which is funded by the US government.

North Korean propaganda showed soldiers wearing rucksacks bearing a yellow and black radiation symbol during a parade celebrating the 70th anniversary of the national Workers' Party in October, while similar backpacks were seen at a procession in 2013.

The report came after Kim Jong-un’s administration reportedly executed a vice premier and banished two other top officials to rural areas for dreaded “re-education”.

South Korean officials said Yong-jin, a cabinet minister for education affairs, had been killed, possibly by a firing squad in July for unspecified anti-revolutionary and factional acts.

Reports said said Kim first faced an investigation because of the way he was seated during a meeting attended by the Supreme Leader.

North Korea's worst human rights abuses Show all 11 1 /11 North Korea's worst human rights abuses North Korea's worst human rights abuses Starvation A UN report said that policies leading to mass starvation in North Korea amounted to crimes against humanity. Deaths peaked during the 1990s North Korean famine. Al Jazeera North Korea's worst human rights abuses Executions Defence minister Hyon Yong Chol is believed to be the latest official executed after falling foul of Kim Jong-un. As well as gruesome public executions, thousands of people have been killed in state 'purges' and for alleged anti-state crimes Getty North Korea's worst human rights abuses Torture Torture is prevalent in prison camps, as well as in police and security service custody. AP North Korea's worst human rights abuses Freedom of religion American missionary Kenneth Bae was one of the many people detained after trying to practice their religion. The DPRK Constitution claims to protect freedom of religion but not if it as alleged of being used a a pretext for 'drawing in foreign forces or for harming the state and social order'. Christianity is frequently considered a political crime North Korea's worst human rights abuses Freedom of expression All media is tightly-state controlled and expressing facts of opinions critical of the government or Juche ideology can lead to arrest and imprisonment. As well as being under extensive surveillance, people are encouraged to 'inform' on friends and neighbours Getty North Korea's worst human rights abuses Freedom of thought A UN report found that the 'DPRK operates an all-encompassing indoctrination machine which takes root from childhood to propagate an official personality cult and to manufacture absolute obedience to the Supreme Leader, effectively to the exclusion of any independent thought from the official ideology and state propaganda' Reuters North Korea's worst human rights abuses Forced labour Prisoners are subjected to forced labour in camps, including children as young as five. Some workers are also reportedly being sent abroad to fund the government's projects AFP North Korea's worst human rights abuses Sexual discrimination Although women are permitted to serve in the military, their role is restrained by the Juche ideology and the UN reports that 'discrimination against women remains pervasive in all aspects of society' AP North Korea's worst human rights abuses Freedom of movement Freedom of movement is severely restricted within North Korea and very few citizens are allowed to leave the country. Immigrants found in China can be forcible repatriated and punished on their return. The right for foreigners to enter is also severely restricted. Reuters North Korea's worst human rights abuses Prison camps Many of the worst abuses reported take place at prison camps, some specifically for political crimes. The camps officially do not exist but have been photographed using satellite. Inmates are 'forcibly disappeared' and usually imprisoned until death REUTERS North Korea's worst human rights abuses Reproductive rights Forced abortions have been reported for imprisoned women, often after being raped by guards. Mothers and babies frequently die in childbirth because of a lack of adequate care, often delivering babies unaided at home. AP

Kim Yong-chol, a top ruling Workers' Party official in charge of anti-Seoul spy operations, and Choe Hwi, a senior party official dealing with propaganda affairs, had been banished to undertake “revolutionary re-education” programmes.

The reported purges came as North Korea continues to intensify its propaganda over joint military exercises being conducted by more than 75,000 American and South Korean troops in “Ulchi Freedom Guardian”.

While the North is known to have a small stockpile of nuclear warheads, experts are divided about its ability to mount them on a working missile delivery system.

In a statement earlier this month by US and South Korean forces described the exercises as “non-provocative in nature” and designed to enhance “readiness, protect the region and maintain stability on the Korean peninsula”.

11 most corrupt countries in world

But the drills provoked a stream of threats from Pyongyang, which said it would turn Seoul and Washington into a “heap of ashes” with a pre-emptive strike.

An editorial published by the state-run Korean Central News Agency on Tuesday accused Barack Obama’s administration of presiding over a “reckless arms build-up” that “cannot but spark off a fresh nuclear arms race among regional countries”.

North Korea has made considerable progress on weapons technology this year, including testing a submarine-launched missile for the first time, but it is unclear whether its nuclear material has been developed into a warhead able to be mounted on a missile.

It conducted its fourth nuclear explosion in January and followed it up with a series of missile tests, in spite of severe United Nations sanctions.