A senior official at North Korea's spy agency defected to South Korea last year, a source said Wednesday, pointing to a rise in defections by North Korean elites disillusioned with the repressive regime.

An unidentified official who worked for the Ministry of State Security escaped to the South last year, the source familiar with Pyongyang's affairs said, in an unusual defection by a North Korean in charge of gathering intelligence and cracking down on ordinary people.

The source said that North Korean leader Kim Jong-un is believed to have been upset by the growing number of elite members defecting.

Seoul's unification ministry said it has no specific information on the defection by the North Korean spy agency's official.

More North Korean elites, including diplomats, have deserted their country in search of freedom, which Seoul says points to signs of cracks in the North's regime.

The North's leader is believed to have ordered the execution of more than 100 state, party and military officials to beef up his iron-fist rule.

In the face of international sanctions, North Korean officials working abroad are under growing pressure to repatriate hard currency to the regime, experts said.

Pyongyang banished its vice foreign minister Kung Sok-ung to a cooperative farm as punishment after the North's leader Kim Jong-un became angry as several North Korean diplomats escaped to South Korea, according to a report by the JoongAng Ilbo.

Kung, a veteran diplomat, was banished to a rural farm in an unidentified area in the wake of Thae Yong-ho's high-profile defection to South Korea, the daily said. Thae was the No. 2 man at North Korea's embassy in London.

Thae defected to Seoul with his family in late July, making him one of the highest-ranking North Korean officials to arrive in the South.

The Seoul government said it is checking relevant information to verify the report over Kung's purge.

Foreign Minister Yun Byung-se said on Oct. 2 that the largest-ever number of elite defectors came to the South over the past eight to nine months, without revealing specific figures.

A North Korean diplomat stationed in Vladivostok, Russia, is believed to have brought a considerable sum of foreign currency to South Korea when he recently defected to the South.

Kim Chol-song, a third secretary at North Korea's trade mission in Russia, is also known to have escaped to Seoul in late July.

North Koreans toiling in overseas countries defected to South Korea earlier this year at a time when Pyongyang has increased its labor exports to secure foreign currency.

In April, a group of 17 North Koreans working at a Pyongyang-run restaurant in China made a rare group defection to the South in the wake of the UN Security Council's sanctions over the North's fourth nuclear test in January.

As of end-September, the number of North Korean defectors reached about 29,830 in total, with 1,036 North Koreans having come to the South in the first nine months of this year, according to data by the Ministry of Unification.

Jeong Joon-hee, spokesman at the ministry, said that Seoul is preparing to overhaul the resettlement system for defectors as the number of such people is set to top the 30,000 mark.

President Park Geun-hye said Tuesday that the government should review the current policy for defectors and come up with a system that can "sufficiently" embrace North Koreans coming to the South.

Early this month, Park said South Korea will keep the road open for North Koreans to find new hope and lives in the South. (Yonhap)