It also insisted that future talks to arrange family reunions must also discuss reopening an inter-Korean tourism program at the Diamond Mountain resort in North Korea, which had been highly lucrative for Pyongyang until it was shut down in 2008. South Korean officials said such demands could prove problematic.

“It’s regrettable that North Korea is linking a humanitarian project to our annual military exercises,” said Kim Eui-do, a spokesman of the Unification Ministry of South Korea. “We hope that North Korea will demonstrate its sincerity through action, rather than just talking about improving relations with the South.”

President Park made her overture five days after Mr. Kim, the North Korean leader, called for improved ties with South Korea during his New Year’s Day speech.

Millions of Koreans were separated from relatives when the Korean Peninsula was divided into the communist North and the pro-American South at the end of World War II in 1945. The subsequent Korean War, which began in 1950, ended in 1953 in a cease-fire, with the peninsula still divided. Since then, no exchanges of letters, telephone calls or emails have been allowed between North and South Koreans, and family reunions remain a highly emotional issue and an indicator of the tense state of relations on the peninsula.

About 22,000 people from both Koreas participated in 18 rounds of government-arranged reunions between 1985 and 2010, when the program was suspended as relations between the two countries soured. About 73,000 South Koreans — half of whom are more than 80 years old — remain on a waiting list for a chance to meet with parents, siblings or children in the North for the first time in 60 years.

The humanitarian program seemed close to being renewed last fall but was scuttled at the last minute. The North demanded that the South resume tours of the Diamond Mountain resort in return for allowing the family reunions. On Thursday, South Korea reaffirmed that it would discuss the tours only after inter-Korean relations have improved significantly enough.