North Korea's deputy ambassador to UNESCO was called back to Pyongyang from Paris on Monday, a diplomatic source said, marking the latest summoning of North Korean diplomats following the recent execution of leader Kim Jong-un's uncle.

Hong Yong, the North's deputy permanent delegate to UNESCO, and his wife were spotted at the Beijing airport before boarding an Air Koryo flight earlier in the day, the source said on the condition of anonymity.

Last week, the North's ambassador to Sweden, Pak Kwang-chol, returned to North Korea. Pak was one of the close aides to the purged uncle, Jang Song-thaek.

"North Korea appears to be intensively carrying out recalls of high-ranking diplomats," the source said.

"A number of North Korean diplomats, trade officials and businessmen, who served as close subordinates of Jang Song-thaek, have been returned home," the source said.

North Korea's ambassador to China, Ji Jae-ryong, has been conducting business as usual, but North Korean diplomats in Beijing "have been recently trying to refrain from outdoor activities," the source said.

Ji, 71, has shared the same political fate as Jang over the past three decades and served as a "linking pin" between Jang and the Chinese leadership since he took up the post in 2010.

Earlier this month, the North's ambassador to Malaysia, Jang Yong-chol, a nephew of the executed uncle, had also been summoned back to the country.

Concerns remain high over North Korea's stability after the Dec. 12 execution of Jang, who had played a key role in helping Kim consolidate his grip on power. Kim, believed to be around 30, took power two years ago following the death of his father.(Yonhap News)