The announcement accused unidentified conservatives in South Korea of “hostility” towards North Korea, but gave no further details.
The postponement of the reunions appears to be a setback after weeks of improving ties between the two nations.
The South Korean government has not yet responded to the statement from the North.
The Koreas were scheduled to hold six days of family reunions from September 25-30 for people separated by the 1950-53 Korean War, after which millions of Koreans were separated from their families when the peninsula was divided.
North Korea’s Committee for the Peaceful Reunification of Korea was quoted as saying: “We postpone the impending reunions of separated families until a normal atmosphere is created for talks and negotiations to be able to move forward.”
“As long as the South’s conservatives deal [with] inter-Korean relations [with] hostility and abuse… such a basic humanitarian issue as family reunions cannot be resolved.”
Correspondents say the reunions are highly symbolic events, and would have been the first in three years.
The program was suspended in 2010 after the North shelled a South Korean border island.
Estimates say there are 72,000 South Koreans on waiting lists for a chance to join the family reunion program, but only a few hundred are selected each time.
Most of them do not know if their relatives are still alive because the exchanging of mail, phone calls, and emails is not allowed between the two Koreas.
The reunions are ususally emotional occasions, in which the families meet in the North for a few days before the South Koreans head home again.
The program began in 2000 with some 17,000 relatives having been briefly reunited. Image/AFP