Thirteen North Koreans working at a restaurant based outside the country have defected to South Korea, the Unification Ministry says, marking the first mass defection since the United Nations passed powerful economic sanctions against the communist country last month.

China says it is restricting trade with North Korea, announcing bans on gold and some coal imports and jet fuel exports, in line with UN sanctions.

President Barack Obama tells a nuclear summit in the US that the threat of a nuclear terrorist attack persists and the world must be resolute in foiling it. More than 50 nations were represented at the summit.

North Korea fires another short-range missile off its east coast on Friday, South Korean officials said, as regional leaders met in Washington to discuss the threat of Pyongyang's nuclear weapons programme.

China and the United States will work together to try and prevent further missile tests by North Korea, US President Barack Obama says.

North Korea warns that its military is ready to attack Seoul's presidential palace unless South Korean President Park Geun-hye apologizes for "treason" and publicly executes officials responsible for what Pyongyang says are plans to attack its leadership.

North Korean leader Kim Jong-Un claimed an "historic" advance in the country's nuclear strike capability with the successful test of a solid-fuel rocket engine, state media say.

North Korea fires five short-range missiles into the sea off its east coast -- the latest in a series of launches ordered by leader Kim Jong-Un amid rising military tensions.

North Korea fires a ballistic missile into the sea, South Korean and US officials say.

The US has called on North Korea to immediately release an American student sentenced to 15 years' hard labour for crimes against the state.

A small artificial earthquake has been detected in North Korea, according to South Korean officials who say it was probably due to "blasting work".

US student Otto Warmbier has been given 15 years hard labour in North Korea for crimes against the state.

As North Korea grappled with a massive famine in the 1990s, scientists were working at an elite institute to find ways to boost then leader Kim Jong-il's longevity - and his libido, a defector says.

North Korea has fired two short-range ballistic missiles into the sea, South Korea's military has said.

North Korean leader Kim Jong-Un says his country has successfully miniaturised a thermo-nuclear warhead, as Pyongyang continues to talk up its nuclear strike capabilities amid rising military tensions on the Korean peninsula.

North Korea warns of "indiscriminate" nuclear strikes on the US and South Korea as they begin their largest ever military drills.

Kim Jong-un says North Korea's nuclear weapons should be ready for use "at any time", state media report.

South Korean defence ministry claims that North Korea fired several short-range projectiles into the sea.

North Korea says it will no longer take part in UN Human Rights Council session examining its rights record.

The US, backed by China, submits a draft resolution to the UN Security Council aimed at imposing tougher sanctions on North Korea.