North Korea has branded a UK-based diplomat who defected to South Korea as "human scum".
Deputy envoy in London Thae Yong-ho and his family are now under the protection of the South.
Without listing his name, the North's Korean Central News Agency said the envoy had been accused of leaking secrets, embezzlement and child rape.
It said the UK had been told in June and had been asked for his return but instead handed him to South Korea.
In a commentary, the KCNA said "[the fugitive] should have received legal punishment for the crimes he committed, but he discarded the fatherland that raised him and even his own parents and brothers by fleeing, thinking nothing but just saving himself, showing himself to be human scum who lacks even an elementary level of loyalty and even tiny bits of conscience and morality that are required for human beings".
The KCNA accused the UK of "handing over the fugitives without passports to the South Korean puppets and neglecting its duty to protect diplomats living in its own country".
Britain's Foreign Office has not commented on the affair.
Mr Thae is thought to be the highest-ranking North Korean official ever to defect.
His main mission in London had been to spread positive perceptions of the North Korean leadership.
Seoul announced on Wednesday that Mr Thae had arrived there but refused to give further details about the defection.
In the past, Mr Thae had argued the British were brainwashed by their ruling class into believing "shocking, terrifying" lies about North Korea under its leader Kim Jong-un.
"If the people in this country, or in America, knew that there is a country in the world where there is a free education, free housing, free medical care, then they'd have second thoughts," he had said in one speech.
The BBC's diplomatic correspondent, James Robbins, said it now looked as if Mr Thae's heart may not have been in the task of defending North Korea.
South Korea spokesman Jeong Joon-hee said: "On his reasons for defection, Minister Thae cited disgust with Kim Jong-un's regime, admiration for South Korea's free, democratic system and the future of his family."