A senior North Korean military officer who oversaw spying operations has defected, say South Korean officials.
The officer has not been named, but the defence ministry in Seoul said he was a senior colonel in the Reconnaissance General Bureau and left last year.
Many thousands of people have fled North Korea since the end of the Korean War, but high level defections are rare.
Government officials were quoted by South Korea’s Yonhap news agency as saying this was a sign the leadership of Kim Jong-un was cracking.
Defence Ministry spokesman Moon Sang-gyun said South Korea could not release further information on the colonel.
But one unnamed official told Yonhap the man was the highest-level military official ever to have defected.
“He is believed to have stated details about the bureau’s operations against South Korea to the authorities here,” said the official.
The Reconnaissance General Bureau handles intelligence gathering and spying operations, as well as cyber warfare, said Yonhap.
The announcement came three days after Seoul revealed that 13 North Koreans working at the same restaurant in a foreign country had defected to the South.
It was the largest group defection since Kim Jong Un took power in late 2011. South Korean media reported that the restaurant is located in the eastern Chinese city of Ningbo.
The Unification Ministry said a North Korean diplomat based in Africa separately defected to South Korea last year.
The reconnaissance agency was believed to be behind two deadly attacks blamed on Pyongyang that killed 50 South Koreans in 2010.
There have been occasional reports of lower-level North Korean soldiers defecting, but it is unusual for a colonel to flee to the South.
The highest-level North Korean who took asylum in South Korea is Hwang Jang-yop, a senior ruling Workers’ Party official who once tutored Kim’s late dictator father, Kim Jong Il.
Hwang’s 1997 defection was hailed by many South Koreans as an intelligence bonanza and a clear sign that the North’s political system was inferior to the South’s. Hwang died in 2010.
According to South Korean government records More than 29,000 North Koreans have fled south since 1953 .
Many defectors have testified they wanted to avoid the North’s harsh political system and poverty.
Pyongyang usually accuses Seoul of enticing North Korean citizens to defect.
The announcement on the defections comes as the two Koreas trade threats amid Pyongyang’s anger over annual South Korean and US military drills that North Korea calls a rehearsal for an invasion.
The North has fired a slew of missiles and artillery shells into the sea in an apparent protest against the drills.
South Korean officials said they disclosed the restaurant workers’ group defection because it was an unusual case and happened after tough sanctions were imposed over Pyongyang’s nuclear test and rocket launches this year.
The officials said they confirmed the two individual defections in response to news reports on them.
Borders between the Koreas are heavily guarded and few people have the resources to fund an escape, analysts say. Many take an overland route through China.