North Korea appears to have declined an invitation to send Catholic believers to a mass celebrated by Pope Francis in Seoul later this month, a South Korean Church official said Tuesday.

Two American citizens facing trial in North Korea called for help from the U.S. government to secure their release from what they feared could be lengthy prison terms, a news report said.

North Korea is asking the U.N Security Council to hold an urgent session to discuss upcoming U.S.-South Korean joint military exercises that Pyongyang described on Friday as a threat to peace.

Deputy representative Ri Tong Il told reporters that the top world body had not responded to the request contained in a July 21 letter, and vowed North Korea will keep up missile launches in response to the planned war games. 

North Korea on Friday warned the United States and South Korea against going ahead with joint war games this month, calling them a rehearsal for nuclear war.

The annual Ulchi-Freedom Guardian exercise, aimed at testing combat readiness for a North Korean invasion, is scheduled to begin August 18.

The family of Kenneth Bae, a U.S. citizen detained in North Korea for nearly two years, voiced anguish Friday after Bae said he felt "abandoned" by the U.S. authorities.

Fresh satellite images suggest North Korea might be wrapping up engine trials on an intercontinental ballistic missile, fuelling speculation of a full-scale flight test to come, a U.S. think-tank said Wednesday.

Development of a working ICBM would be a game-changing step, bringing the continental United States into range and adding a whole new threat level to the North's regular nuclear-strike warnings.

South Korean activists on Wednesday launched balloons across the border with North Korea carrying thousands of Choco Pies -- a favored chocolate snack that has become the target of a reported crackdown.

Around 200 anti-Pyongyang activists released 50 large helium balloons carrying 350 kilograms (770 pounds) of snacks, including 10,000 Choco Pies from a park in the border city of Paju, organizers of the event said.

North Korea has denounced allegations that it supplied missiles to Hamas and material support to Hizbullah as "sheer fiction" and a "sinister" effort to link Pyongyang to Middle East disputes.

The rebuttal from the foreign ministry was carried in a statement late Monday by the North's official KCNA news agency.

South Korea's military confirmed Tuesday the apparent suicides of two army privates, raising fresh questions over the deployment of young conscripts in frontline units after a deadly shooting spree last month.

The two privates, identified by their surnames Shin and Park, were both found hanged in their barracks on Sunday in separate locations near the heavily militarized border with North Korea, an army spokesman said.

A top-ranking North Korean military official has threatened a nuclear strike on the White House and Pentagon after accusing Washington of raising military tensions on the Korean peninsula.

The threat came from Hwang Pyong-So, director of the military's General Political Bureau, during a speech to a large military rally in Pyongyang Sunday on the anniversary of the armistice that ended the 1950-53 Korean War.