Senior politicians and business leaders in North Korea are expressing their discontent and turning away from Kim Jong-un's regime, the country’s former ambassador to the UK has claimed.

The young leader has caused unrest among the country’s elite by “purging officials for no proper reasons” and making other irrational decisions, Thae Yong-ho told reporters at his first foreign news conference.

When he defected to South Korea last summer, he became the most senior official to do so in two decades.

More North Korean diplomats were preparing to follow his lead, he said.

“When Kim Jong-un first came to power, I was hopeful that he would make reasonable and rational decisions to save North Korea from poverty, but I soon fell into despair watching him purging officials for no proper reasons,” he said.

“Low-level dissent or criticism of the regime, until recently unthinkable, is becoming more frequent," he added. "We have to spray gasoline on North Korea, and let the North Korean people set fire to it.”

Mr Thae said he fled North Korea after becoming dissatisfied by Mr Kim’s increasingly erratic actions. He added that he did not want his sons to grow up living “miserable” lives.

Kim Jong-un inspects military exercises and missile launch Show all 11 1 /11 Kim Jong-un inspects military exercises and missile launch Kim Jong-un inspects military exercises and missile launch The North Korean leader inspects a missile launch from a safe distance Kim Jong-un inspects military exercises and missile launch Kim Jong-un discusses plans with military leaders Kim Jong-un inspects military exercises and missile launch A ballistic rocket of the type launched by the DPRK in defiance of UN sanctions Kim Jong-un inspects military exercises and missile launch UN officials tracked two ballistic missile launches from North Korea on Friday 18 March Kim Jong-un inspects military exercises and missile launch The Supreme Leader laughed with officials as the missiles were fired Kim Jong-un inspects military exercises and missile launch Kim Jong-un was also pictured observing military exercises Kim Jong-un inspects military exercises and missile launch Tanks fire missiles during military manoeuvres at an undisclosed location Kim Jong-un inspects military exercises and missile launch The exercises are timed to coincide with military drills by the US and South Korea Kim Jong-un inspects military exercises and missile launch As well as a tank-driving competition, amphibious craft carried out landing and anti-landing exercises Kim Jong-un inspects military exercises and missile launch Including paramilitary reserves, the North Korean army is the largest in the world Kim Jong-un inspects military exercises and missile launch The Supreme Leader appeared pleased with the show of force

Kim Jong-un might be willing “to attack Los Angeles” and other large US cities with nuclear weapons in the future, if he feels his country is being threatened, Mr Thae said.