South Korea has voiced regret after North Korea offered no response to a proposal for talks on resuming reunions for families separated by the 1950-53 Korean War.

In a cross-border message earlier this week, Seoul's Unification Ministry had suggested working-level talks on Wednesday to work out details for holding a reunion event.

But as of Wednesday morning, the North had yet to respond.

"We find it regrettable that the North is showing such an attitude after the two Koreas have already agreed to hold the family reunion," the Unification Ministry said in a statement.

"The aged members of the separated families are anxiously waiting for a chance to reunite with their relatives," it added.

North Korea unexpectedly announced on Friday that it was willing to hold a reunion event -- the latest in a series of conciliatory gestures from Pyongyang that the South has treated with scepticism.

Pyongyang said the dates could be chosen by the South, which promptly suggested February 17-21 at the North's Mount Kumgang resort.

That would sandwich the gathering between the February 16 birthday of North Korea's late leader Kim Jong-Il -- an important national holiday -- and annual South Korea-US joint military exercises that are scheduled to begin at the end of the month.

"Given the North said we could set the date... we urge the North to accept our proposed dates and respond to the requested working-level meeting as quickly as possible," the Unification Ministry said.

The South-US drills are held every year and are routinely condemned by the North as a rehearsal for invasion.

Pyongyang has made several demands that this year's exercises be called off, but Seoul insists they will go ahead.

A reunion event had been planned last September but Pyongyang cancelled at the last minute, and there are concerns it will do the same this time around, citing the military drills as the reason.

The first reunions were held in 2000 following an historic inter-Korean summit. Sporadic events since then have seen around 17,000 relatives briefly reunited.

But the programme has been suspended since the North's shelling of a South Korean border island in November 2010.

Millions of Koreans were left separated by the 1950-53 conflict which sealed the peninsula's division.

Most have died without seeing their relatives again, with personal cross-border contact, including postal and phone communication, banned for decades.

Only about 100 people on each side are selected for each event.