Image copyright Getty Images Image caption It is confirmed that Mr Thae (seen on the right in this file picture) is in South Korea

A top North Korean diplomat who disappeared from the country's embassy in London has defected to South Korea, officials in Seoul have confirmed.

Thae Yong-ho and his family are under the government's protection, a South Korean official said.

Mr Thae was the ambassador's deputy and 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.

He had been due to return to Pyongyang with his wife and children.

Mr Thae had come under pressure from his government to quash growing criticism of North Korea's human rights record, sources say.

The BBC's diplomatic correspondent, James Robbins, says it now looks as if Mr Thae's heart may not have been in the task of defending North Korea.

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.

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."