A senior official at North Korea’s spy agency defected to the South last year, a news report said Wednesday, marking the latest in a recent series of elites seeking to escape from political oppression and the crumbling economy amid a tightening sanctions network.

The director-general level official of North Korea's Ministry of State Security has told Seoul officials that the popular sentiment around Pyongyang was “boiling” with discontent about leader Kim Jong-un’s ironfist rule, Yonhap News Agency reported, citing an unidentified source familiar with North Korean affairs.

The ministry, better known as “Bowibu,” is a chief security and intelligence agency that runs a secret police organization tasked with hunting down those suspected of anti-state and dissident activities and other political and economic crimes.

Upon learning that the official had fled, Kim Jong-un expressed unease, the report added.

The South Korean Unification Ministry spokesperson Jeong Joon-hee declined to confirm the latest defector, citing the lack of information.

The report follows other high-profile defections in recent years involving senior military officers, diplomats and overseas workers.

In August, Seoul unveiled the arrival of Thae Yong-ho, a minister of the North Koran Embassy in London, followed by the defection late last month of an official at the embassy in Beijing with his family. The second official was reportedly responsible for sourcing medical supplies for a Pyongyang clinic overseeing the health of the ruling family.

In April, a group of 13 employees from a North Korean restaurant in China took asylum here.

A colonel-level officer with the Reconnaissance General Bureau, a military intelligence organization, also came to the South last year, in addition to a diplomat in an African nation and his family.

While a steady inflow of defectors has for years been business as usual, the perceived growth of departures among the relatively privileged class may point to economic trouble in the communist state further deepened by international sanctions over its nuclear program.

The cash-strapped regime has thus been forcing diplomats and other overseas workers to find new ways to secure hard currency, sometimes by breaking the law, or face punishment, some defectors say.

The number of North Korean defectors has shot up more than 20 percent on a yearly basis to 1,036 between January and September this year, Unification Ministry records shows.

The share of those with college education or higher has also steadily risen, reaching 5.3 percent in 2012, 6.6 percent in 2013, 6.6 percent in 2014 and 7.3 percent in 2015.

Data from the Korea Hana Foundation, a Unification Ministry affiliate offering resettlement support, show that doctors, teachers, researchers and other professionals make up about 5 percent of those who have come to South in the last three years, twice as many as that among defectors who have been staying here for five to 10 years.

The ongoing getaways, especially of diplomats like Thae, have prompted Kim to expel Vice Foreign Minister Kung Sok-ung to a rural cooperative farm as punishment, according to a separate report by the JoongAng Ilbo daily.

The spokesperson Jeong said the Unification Ministry is looking into information to verify the report.

“Next month, the number of North Koreans here will likely reach 30,000. In line with that, we’re seeking to refine our defector policy in a way that promotes social integration,” he said at a news briefing.

“We’re now working to tackle the existing system’s problems and make our resettlement support system more effective.”

By Shin Hyon-hee (heeshin@heraldcorp.com)