Seoul, Jun 25 (IANS): Seoul on Sunday urged North Korea to release six South Koreans and three Americans held in prison.

"North Korea must release our citizens and Americans currently in prison there," said South Korean Prime Minister Lee Nak-yeon, in a ceremony at the Seoul Olympic Stadium to commemorate the 67th anniversary of the onset of the Korean War, reports Efe news.

North and South Korea are technically still at war since the 1950-53 Korean War, ended with an armistice that has not been replaced with a peace treaty.

He added that the international community is infuriated by the death of American Otto Warmbier who died six days after North Korea freed him on June 13.

"The Kim Jong-un regime must step forward to achieve the denuclearization on the peninsula and respect human rights," the Premier added.

North Korea currently has three more American citizens imprisoned, two of them detained in April and May.

Six South Koreans, of whom three are Christian pastors, and ae Canadian also also imprisoned in North Korea. All of them are accused of having committed crimes against North Korea.