North Korea said Monday its titular head of state would attend a World War II anniversary in Russia this week, after leader Kim Jong-Un cancelled his much-anticipated trip to the Moscow event.

Kim Yong-Nam, the president of the North's rubber-stamp parliament, will participate in the May 9 ceremony to mark the 70th anniversary of the Soviet victory over Nazi Germany, state-run news agency KCNA said.

Two South Koreans awaiting trial in North Korea on espionage charges have admitted to spying for Seoul in interviews with CNN in Pyongyang conducted in the presence of North Korean minders.

The television news network said it had been unable to independently verify the accounts provided by the two men, who were interviewed separately in different rooms of a Pyongyang hotel on Sunday.

North Korean leader Kim Jong-Un vowed to launch more "satellites" in order to become a space power, state media said Sunday, despite global condemnation on past launches, dubbed disguised ballistic missile tests.

Kim, during a visit to the North's newly-built satellite command centre, urged scientists to work harder to "further glorify the (North) as a space power," state-run KCNA said. 

North Korean diplomats on Thursday walked out of a U.N. conference on human rights in protest at the testimonies from three defectors about their ordeal living under the regime.

A Pyongyang representative interrupted the conference when he tried to deliver a statement after dissident Joseph Kim had given his address. He was told he would be given an opportunity to make a statement later.

North Korean leader Kim Jong-Un has canceled his planned visit to Moscow to attend Russia's World War II anniversary celebrations on May 9, President Vladimir Putin's spokesman said on Thursday.

"He will not come. This is related to internal North Korean issues," Putin's spokesman Dmitry Peskov told AFP, saying the message had been received "through diplomatic channels."

In a rare display of political unity, South and North Korea on Thursday both condemned Japanese Prime Minister Shinzo Abe for failing to apologize during a U.S. visit for the wartime use of sexual slaves.

Their respective foreign ministries each issued statements criticizing Abe for distorting history, with Pyongyang comparing the Japanese leader to "psychopaths" and "hooligans".

North Korea's Kim Jong-Un ordered the execution of 15 senior officials this year, including several who complained about the young leader's policies, South Korea's intelligence agency said Wednesday.

Those executed included two vice minister-level officials, the Yonhap news agency reported, citing legislators who attended a briefing by the National Intelligence Service (NIS).

North Korea has increased its "material support" for terrorist organizations and should be placed back on America's list of nations that are state sponsors of terrorism, a report released Monday said.

The Pyongyang regime, at the time under the command of Kim Jong-il, was taken off the list in 2008 under the presidency of George W. Bush, who hoped to engage the reclusive nation in dialogue. 

The United States said Thursday that any deal reached with Iran to curb its nuclear ambitions would be "fundamentally different" from a pact sealed with North Korea that later unraveled.

"The restrictions, inspections and verifications measures imposed on Iran by a comprehensive plan of action will go far beyond those placed on North Korea in the 1990s and the 2000s," said acting State Department spokeswoman Marie Harf.

Russia is still expecting North Korean leader Kim Jong-Un to visit Moscow in May, with a possible summit scheduled with President Vladimir Putin, Russia's ambassador to South Korea said Thursday. 

In a press briefing at the embassy, Alexander Timonin confirmed Kim, who has yet to travel abroad since coming to power more than three years ago, was on course to attend Moscow's World War II anniversary celebration on May 9.