South Korea's spy agency Wednesday detained a leftist lawmaker accused of plotting an armed revolt in support of North Korea after parliament voted to approve his arrest.

The National Intelligence Service (NIS) took United Progressive Party (UPP) legislator Lee Seok-Ki away from his office in parliament after a confrontation with his supporters.

North Korean leader Kim Jong-Un has made his third visit in a year to highly fortified frontline islands on the disputed maritime border with South Korea, state media said Tuesday.

His latest tour of Jangjae Island and Mu Island was less dramatic than his last visit during soaring military tensions in March, when he threatened to "wipe out" the nearby South Korean island of Baengnyeong

North Korea said it rescinded its invitation for a U.S. envoy to visit the country to seek the freedom of an American detainee because Washington perpetrated a "grave provocation" by allegedly mobilizing nuclear-capable bombers during recent military drills with Seoul.

The moves signal that possible informal negotiations between the two countries over detainee Kenneth Bae were not going smoothly, with Pyongyang seeking some concessions from Washington in return for releasing the man, analysts said.

U.S. spy services conducted 231 "offensive cyberoperations" in 2011, mostly targeting Iran, Russia, China and North Korea, the Washington Post reported Saturday.

The revelation is based on a classified intelligence budget provided to the paper by fugitive leaker Edward Snowden, as well as on interviews with former U.S. officials.

North Korea on Saturday blamed Washington for the cancellation of a visit by a special American envoy to Pyongyang, citing joint U.S.-South Korea military drills described as the "most blatant nuclear blackmail".

On Friday, the U.S. State Department said North Korea had cancelled the invitation to an envoy who was to have sought the release of an American citizen held prisoner in the reclusive state.

Fresh satellite imagery shows North Korea has embarked on a major new construction program at the facility where it launched a long-range rocket in December, a U.S. research institute said.

The construction includes what could be a possible new launch pad for testing mobile ballistic missiles, the U.S.-Korea Institute at Johns Hopkins University posted on its 38 North website Friday.

North Korea has cancelled its invitation to a U.S. envoy who was to have sought the release of an American citizen it holds prisoner, the State Department said Friday.

News of the planned trip by U.S. diplomat Robert King had raised hopes that Kenneth Bae, a 44-year-old American who has been prisoner in North Korea since November, might be released.

The head of a U.N. probe Friday urged North Korea to respond to horrific testimony of human rights abuses heard in Seoul and Tokyo.

Retired Australian judge Michael Kirby, who led the three-member Commission of Inquiry, also called for increased awareness about the plight of some 95,000 formerly Japan-based ethnic Koreans who migrated to North Korea decades ago.

North Korea's top military body lashed out Thursday at an ongoing South Korea-U.S. army drill, warning that it could compromise a recent easing of military tensions on the Korean peninsula.

The criticism from the North's National Defense Commission marked the first high-level rebuke of the 10-day Ulchi Freedom Guardian joint exercise, which ends on Friday.

A United Nations team probing North Korea's human rights record was in Japan on Wednesday, as Tokyo campaigns to publicize the kidnapping of its nationals by Pyongyang agents.

The three-member Commission of Inquiry chaired by retired Australian judge Michael Kirby spent five days in Seoul collecting harrowing testimony of rights abuses in the North from defectors.