North Korea has sentenced two South Koreans accused of spying to hard labor for life, South Korea's Yonhap news agency said on Tuesday, citing a North Korean state radio broadcast.
North Korea has accused the two men arrested in March of working as spies for the South's National Intelligence Service (NIS) from the Chinese border city of Dandong.
The NIS has denied the accusations as "groundless." The South has urged the North to release four of its citizens, including the two, Kim Kuk Gi and Choe Chun Gil, who said in interviews with CNN in May that they had spied for the South.
The pair were charged with conspiracy to overturn the state, espionage and illegal entry and were accused of working under the control of the U.S. and South Korean governments, Yonhap cited the North Korean radio broadcast as saying.
South Korea's Unification Ministry, which handles ties with the North, could not immediately confirm the North's broadcast.
North and South Korea are still technically at war after their 1950-53 conflict ended in a truce, not a treaty. The reclusive North, which regularly threatens to destroy the United States in a sea of flames, has also been slapped with heavy Western sanctions over its nuclear and missile programs.
North Korea's state media has accused one of the two prisoners of running an "underground church" and spreading foreign information.
In addition to the two, Pyongyang is holding a South Korean man with a U.S. green card who was a student at New York University, as well as a South Korean missionary who was sentenced to life with hard labor last year for espionage and setting up an underground church.
Last year, Pyongyang released three detained Americans including Kenneth Bae, a Korean-American missionary who had been held for two years.