South Korea has called on North Korea to honour its promise to hold a reunion of families from the two countries who have separated for decades, after days of silence by the North's government.
The North unexpectedly announced last week that it was willing to hold a reunion and the South on Monday suggested holding working-level talks to arrange details.
But the North has made no response since then and the South's unification ministry warned it against repeating empty promises of reunions.
"[The North] should not repeat yet again, breaking the hearts of separated families who have been longing for the reunion," said ministry spokeswoman Park Soo-Jin.
"The separated families will suffer less if they [North Koreans] don't make promises that they can't keep," she said, urging the government in Pyongyang to prove its sincerity with action.
In making its announcement last week, the North said the dates could be chosen by the South, which promptly suggested 17-21 February at the North's Mount Kumgang resort.
If it goes ahead, the event will be the first since 2010.
A reunion was planned last September but the North cancelled at the last minute. There are concerns it will do the same this time around, due to planned joint South Korean-US military drills likely to begin in late February.
The exercises are held every year but are routinely condemned by the North as a rehearsal for invasion.
North Korea has made several demands that this year's exercises be called off but South Korea and the US said they would press ahead with what they call defensive drills.
Millions of Koreans were left separated by the 1950-53 conflict that sealed the peninsula's division.
Most have died without meeting or talking to their relatives since cross-border visits and postal and phone communication are banned for ordinary people.
About 71,000 people - more than half aged over 80 - are on the South's waiting list to take part in a reunion, in which family members from the two sides typically meet in the North for two or three days.
But only around 100 people on each side are chosen for each event.