North Korea Thursday rejected a South Korean proposal for resuming reunions for families separated by the Korean War, citing planned South-US military exercises as a major barrier.

The North's main body for inter-Korean affairs said it would like to get the reunions going again, but questioned the South's sincerity.

"How could separated families comfortably meet for a reunion in the face of ceaseless war practices staged in the South?" the Committee for the Peaceful Reunification of Korea (CPRK) was quoted as saying by the North's official KCNA news agency.

Earlier this week South Korean President Park Geun-Hye had called for a reunion to be held around the time of the Lunar New Year on January 31.

In a press conference, Park said the reunion programme would provide new momentum to improving ties following years of high tensions.

A reunion had been scheduled for September last year, but Pyongyang cancelled it at the last minute, blaming "hostility" from South Korea.

"In contrast to our genuine efforts, press experts and even government officials in the South made rude comments and displayed bad behaviour," the CPRK recalled in its message Thursday to the South's Unification Ministry.

Seoul responded by expressing "regret" that Pyongyang had sought to link a humanitarian issue with the joint military exercises the South conducts every year with the United States.

Millions of Koreans were left separated by the Korean War, which sealed the peninsula's division. Most have died without having the chance to reunite with family members last seen six decades ago.