The wife of North Korean dictator Kim Jong-un has not been seen in public for seven months prompting speculation that she is either pregnant or has fallen out of favour.

Experts monitoring the situation in Pyongyang have suggested Ri Sol-ju, who was introduced as First Lady in 2012, may have fallen out with Kim Jong-un’s younger sister, Kim Yo-jong, who is increasingly regarded as the power behind the throne.

Kim Yo-jong was put in charge of North Korea’s Propaganda and Agitation Department last year and is responsible for building up her brother’s cult of personality.

Ri was last seen on a tour of a new commercial district and health complex in Pyongyang on 28 March, South Korean news agency Yonhap News reported.

In contrast Kim Jong-un has frequently been seen touring the country and hosted the country’s first party congress in 36 years in May.

Toshimitsu Shigemura, a professor at Tokyo’s Waseda University who focuses on the Pyongyang leadership, told The Telegraph Ri’s disappearance could be down to several factors.

What you're not allowed to say in North Korea

He said: "There are several possible reasons, including that she is pregnant or that there is some sort of problem between the two of them.

"There have also been reports of instability in Pyongyang and even of several attempted attacks, including by factions in the North Korean military, against Kim last year.

"It is possible that Ri has not appeared in public because she is being closely guarded."

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He said Kim Yo-jong held a great deal of influence over her brother as it is believed “that while Mr Kim lacks political ability, she is far more adept at the sort of manoeuvring that is required to keep him in power, so that is the task she has taken on”.

Ri last disappeared from public view in 2012 prompting speculation that she had fallen out of favour or was pregnant.

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In 2013, former US basketball star Dennis Rodman - who has become an unlikely friend to the regime - revealed she had given birth to a daughter in late 2012.

But Kim Jong-un is not above disposing of those closest to him if they fall out of favour.

He executed his uncle, Jang Sung-taek, after finding him guilty of treason despite their relationship being reportedly close beforehand.