S. Korea demands release of pair North accuses of spying

South Korea demanded on Friday the immediate release of two of its citizens that North Korea said it had arrested, accusing them of spying for the South.

Late on Thursday, the North's official KCNA news agency showed images of two middle-aged men it identified as Kim Kuk Gi and Choe Chun Gil speaking at a news conference in the North Korean capital, Pyongyang.

It said the two men were South Korean nationals working as spies for Seoul's National Intelligence Service from the Chinese border city of Dandong.

"They zealously took part in the anti-DPRK smear campaign of the U.S. imperialists and the puppet group of traitors to isolate and blockade the DPRK in (the) international arena," the agency said, using North Korea's official DPRK acronym for Democratic People's Republic of Korea.

On Friday, Lim Byeong Cheol, a spokesman at South Korea's Unification Ministry confirmed that Kim and Choe were South Korean citizens but denied they were engaged in espionage operations. Ministry officials could not explain how the two ended up in the North.

"We strongly demand North Korea to quickly release our citizens Kim Kuk Gi and Choe Chun Gil and repatriate them without hesitation," Lim said.

South Korea's National Intelligence Service, the country's main spy agency, denied the North's accusations of spying.

The North's Korean Central News Agency said Kim was detained in September in Pyongyang and Choe near the border with China in December.

North Korea has occasionally detained South Korean nationals in the past on accusations of spying in what outside experts say are attempts to pressure Seoul or raise North Korean people's hostility toward the South.

North Korean state media accused one of the men of running a China-based "underground church" and illegally spreading foreign information on USB sticks and SD memory cards in the country.

Dandong is home to many ethnic Korean Chinese traders who deal with both North and South Korean businessmen. It is also home to South Korean and Christian missionaries from the West trying to operate in North Korea.

The KCNA article did not say how or where the two men had been arrested.

North Korea has held South Korean missionary Kim Jeong-wook since October 2013 on allegations of espionage, despite pleas from Seoul to release him. He was given a life sentence of hard labor.

In February, a South Korean-born Canadian pastor went missing during a humanitarian mission in the North and his church said earlier this month he was being detained there.

Last year, a Canadian Christian couple who worked with North Korean refugees and ran a coffee shop in Dandong were accused of espionage by the Chinese government.

Korean-American missionary Kenneth Bae was released last year after being sentenced by the North Korean government on charges of trying to bring down the state.

The latest incident comes amid ongoing regular military drills between South Korea and the U.S., which Pyongyang calls a rehearsal for an invasion. South Korean and U.S. officials say the drills are defensive in nature.

Thursday also marked the fifth anniversary of a sinking of a South Korean warship that Seoul officials blame on a torpedo attack by the North. Pyongyang has denied any involvement in the sinking that killed 46 South Korean sailors.

Wire services