SEOUL -?The Republic of?Korea's unification ministry in charge of inter-Korean relations on Friday urged the Democratic People's Republic of Korea (DPRK) to immediately return two?citizens who have been detained in the DPRK on charge of espionage.

"It is very regrettable that North Korea (DPRK) makes an absurd claim about our nationals Kim Kuk-gi and Choe Chun-gil unilaterally detained (in the DPRK) without giving any advance explanations about it to our government," the Unification Ministry said in a statement.

The statement came after the DPRK's Korean Central News Agency (KCNA) reported Thursday that a press conference was held for the two detained?ROK citizens?at the People's Palace of Culture in Pyongyang.

The report claimed that the two men were arrested for conducting anti-DPRK smear campaign and gathering information on the DPRK's state and military secrets on behalf of the National Intelligence Service (NIS), the ROK's spy agency.

The ministry said that what the KCNA reported should be reviewed after the two are repatriated to Seoul, urging the DPRK to immediately release Kim and Choe and guarantee their safety and convenience before their release.