A North Korean diplomat stationed in the British capital has defected to South Korea with his family, South Korean authorities said Wednesday.

Mr Thae defected due to discontent with the regime of Mr Kim Jong Un in North Korea and for the future of his child, ministry spokesman Jeong Joon Hee told a news conference. Thae told South Korean officials that he defected because of his disillusionment with Kim Jong Un's regime and his yearning for freedom, Jeong said.

Thae was the second highest-ranking diplomat in the North Korean embassy in London after Ambassador Hyon Hak-bong, Jeong added.

This is an image taken from video taken on April 5, 2004 of Thae Yong Ho, North Korean diplomat speaking during an interview in Pyongyang.

Thae served as North Korea's No.2 official at its embassy in London and is the senior-most North Korean diplomat to defect from the repressive country in almost two decades. So far this year, 815 people defected to South Korea, up 15.6 percent from the same period in the prior year, according to government data cited by South Korean news agency Yonhap.

The live-fire exercise was timed for the eve of the first anniversary of an artillery exchange between the two countries after land mine explosions wounded two South Korean soldiers, military officials said.

Thae Yong Ho has worked in the embassy for over a decade and is prominent among the British media as the main contact for United Kingdom journalists who wish to travel and cover news in Pyongyang.

"It is one thing to blame South Korean intelligence for misleading a dozen young waitresses working overseas, it would be another thing entirely for the DPRK to assert that a seasoned diplomat was in fact defecting under duress", Cathcart said. North Korea conducted its fourth nuclear test in January, and South Korea has been working hard to apply more worldwide pressure on the North.

Several analysts questioned whether a defection by Thae signals discontent with the current regime. The South Korean government is placing particular emphasis on the fact that the increase in defectors shows the effectiveness of sanctions against North Korea.

The US government is increasingly concerned that advances in North Korea's weapons program have dramatically decreased the warning time for a nuclear attack on America or its allies, according to US officials. "Thae's sons had spent about 10 years overseas, and it might have been hard for them to go back to Pyongyang", one expert on defector issues said.

Thae had last drawn attention when he was spotted previous year in London attending an Eric Clapton concert with Kim Jong Chol, older brother of Kim Jong Un.

Those who still managed to flee in recent years often had families already settled in the South, or were relatively well-off and well-connected members of the elite in search of better lives.

He was credited with developing the North Korean ideology of "juche", or "self-reliance".