South Korea’s spy agency said on Tuesday that a senior North Korean diplomat based in Cuba has fled to South Korea, the latest defection by members of the North’s ruling elite that is likely to have hit leader Kim Jong Un’s push to bolster his leadership.

The National Intelligence Service confirmed that media reports on the defection of a North Korean counsellor of political affairs in Cuba are true, but a brief statement by the NIS public affairs office gave no further details.

South Korea’s mass-circulation Chosun Ilbo newspaper reported earlier on Tuesday that diplomat Ri Il Kyu fled to South Korea with his wife and children in November.

Chosun Ilbo cited Mr Ri as telling the newspaper in an interview that he had decided to defect because of what he called disillusionment with North Korea’s political system, an unfair job evaluation by Pyongyang’s Foreign Ministry, and the ministry’s disapproval of his hopes to visit Mexico to treat his neural damage.

He said hospitals in Cuba did not have the necessary medical equipment to treat his health problem due to international sanctions.

Other South Korean media outlets carried similar reports later on Tuesday.

North Korea did not immediately respond to South Korea’s announcement of Mr Ri’s defection.

North Korea has previously expressed fury over some high-profile defections, accusing South Korea of kidnapping or enticing its citizens to defect. It has also described some defectors as traitors or criminals who fled to avoid punishment.

Mr Ri defected before South Korea and Cuba established diplomatic ties in February, an event that experts say is likely to have dealt a political blow to North Korea, whose diplomatic footing is largely dependent on a small number of Cold War-era allies like Cuba.

The Chosun report said Mr Ri had been engaged in efforts to block Cuba from opening diplomatic ties with South Korea until his defection.

The report said he had won a commendation from Kim Jong Un for his role in negotiations with Panama that led to the release of a ship detained in 2013 for allegedly carrying banned items like missiles and fighter jet parts. The report said that at the time Mr Ri was a third secretary of the North Korean Embassy in Cuba.

About 34,000 North Koreans have defected to South Korea to avoid economic hardship and political suppression, mostly since the late 1990s. A majority of them are women from the North’s poorer northern regions. But the number of highly educated North Koreans with professional jobs escaping to South Korea has steadily increased recently.

In 2023, about 10 North Koreans categorised as members of the country’s elite group resettled in South Korea – more than in recent years, according South Korea’s Unification Ministry.

Ministry officials have said that an increase in high-level defections is likely to have been due to North Korea’s pandemic-related economic difficulties and its pushes to reinforce state control of its people.

Those who had to stay abroad longer than initially scheduled due to Covid-19 curbs were exposed to freer foreign cultures for an extended period.

“This high-level defection adds insult to injury for North Korea, as Ri was instrumental in representing Pyongyang’s interests in Havana,” said Leif-Eric Easley, professor of international studies at Ewha Womans University in Seoul.

“The Kim regime is no doubt taking measures to make it more difficult for diplomats overseas to defect, but increased repression is likely to further isolate Pyongyang and may actually encourage more defections.”

Moon Seong Mook, an expert with the Seoul-based Korea Research Institute for National Strategy, said news of high-level defections like Mr Ri’s will spread to North Korean diplomats and others, potentially dealing a big blow to Mr Kim – although it is unlikely to lead to a regime collapse.

Few North Korea monitoring groups question Mr Kim’s grip on power, but observers say the leader is grappling with chronic economic difficulties, the influence of South Korean pop cultures and the expansion of the US-South Korean military co-operation.

The most high-profile defection in recent years happened in 2016, when Tae Yongho, then a minister at the North Korean Embassy in London, arrived in South Korea.

He said he had decided to flee because he did not want his children to live “miserable” lives in North Korea as he also fell into “despair” over Mr Kim’s execution of officials and his pursuit of nuclear weapons.

North Korea has called him “human scum” and accused him of embezzling government money and committing other crimes. Mr Tae was elected to South Korea’s parliament in 2020.

In 2019, North Korea’s acting ambassador to Italy, Jo Song Gil, arrived in South Korea, and also that year North Korea’s acting ambassador to Kuwait went to South Korea with his family.

In recent months, tensions on the Korean Peninsula have soared over North Korea’s launches of rubbish-carrying balloons towards South Korea and its continuation of missile tests.

North Korea has said its balloon campaigns are a tit-for-tat action against South Korean activists floating political leaflets via their own balloons.

On Tuesday, Mr Kim’s sister and senior official, Kim Yo Jong, warned South Korea of unspecified “gruesome” consequences, saying that South Korean-sent leaflets had again been found in the North. She issued a similar warning on Sunday.

South Korea responded to North Korea’s earlier balloon activities by suspending a 2018 tension-reduction deal with North Korea.