Questions about Kim’s health spread after Chang Song-min, who advised a former South Korean president, claimed he had been in a coma since April. In response Mr Chang said Kim Yo-jong, who is four years younger than her brother, was being “brought to the fore” to prevent a political vacuum emerging.

However, on in late August North Korea’s state controlled KCNA news agency released pictures which appeared to show Kim taking part in a meeting with other top North Korean officials.

According to the New Zealand Herald Kim is “furious” at reports his sister was being readied to replace him.

As Kim Yo-jong hasn’t been seen in public since July 27 this has sparked speculation she may have been purged.

Kim’s older half-brother, Kim Jong-nam, was murdered in 2017 by a nerve agent in Malaysia.

The North Korean state is widely regarded as having been behind the attack.

Speaking to South Korean news site Chosun Ilbo Professor Nam Sung-wook of Korea University said being seen as Kim’s heir apparent was a dangerous position.

He commented: “In the past, anyone was deprived of their position the moment they were described as the number two person in the North.

“There must be a semblance of checks and balances, although Kim Yo-jong is a family member.”

READ MORE: North Korea – ‘Death by firing squad’ warnings exposed amid purge fears

Further lockdown measures were introduced nationwide after a man reported COVID-19 like symptoms but the World Health Organisation later said tests were inconclusive.

Speaking to Voice of America about the situation inside North Korea a source within the country said: “All international borders remain closed.

“Supplies coming to Nampo seaport remain suspended as there are no ships sailing in from China’s Dalian port where COVID-19 cases were detected.

“Only Covid-19-related shipments are being allowed through Sinuiju-Dandong border,” a North Korean source told Voice of America.”

However, on August 28 thousands gathered in North Korea’s capital Pyongyang to celebrate the country’s Youth Day.

Last month Chang Song-min caused controversy by repeating his claim that Kim could be seriously ill.

He said: “I assess him to be in a coma, but his life has not ended.

“A complete succession structure has not been formed, so Kim Yo-jong is being brought to the fore as the vacuum cannot be maintained for a prolonged period.”

However, the claim was rejected as “absurd” by Shinmoongo, a leading South Korean news site.