SEOUL (AFP) - South Korea on Wednesday accused North Korea of flying a suspected spy drone across the border during talks last week aimed at ending a military standoff that had pushed the neighbours to the brink of an armed clash.

A radar detected the flight of a suspected unmanned aerial vehicle first on Aug 22 in the demilitarised zone (DMZ), which bisects the Korean peninsula, Seoul's joint chiefs of staff (JCS) said.

"It has been seen flying close to the southern perimeter of the DMZ several times, but we failed to intercept it," a JCS spokesman told AFP.

The flights took place after the two Koreas began high-level marathon talks to de-escalate tensions, which had flared after a mine planted on the border maimed two South Korean soldiers.

Under a deal struck last week, Seoul switched off loudspeakers blasting propaganda messages into the North after Pyongyang expressed regret over the mine blast.

The drone flights were believed to be aimed at monitoring South Korea's military posture along the border as the two rivals remained on high military alert, Yonhap news agency said.

The intrusion sparked an anti-aircraft warning and prompted South Korea to send an attack helicopter and an fighter jet to track down the drone, without success, it said.

In September last year, a South Korean fisherman found the wreckage of a North Korean drone in his net near a frontline island south of the rivals' disputed Yellow Sea border.

A few months earlier crashed drones equipped with cameras were found in three different places near the border.

After a joint investigation with US experts, Seoul claimed at the time that the recovered drones were flown from North Korea and had been pre-programmed to fly over South Korean military installations.

North Korea denied any involvement and accused the South of "fabricating" the evidence.