SEOUL (AFP) - South Korean activists said they launched more than one million anti-North Korean leaflets across the border on Friday, a move likely to infuriate Pyongyang, which has demanded that Seoul ban such exercises.

The leaflets were in bundles attached to 24 gas-filled balloons that a North Korean defector group floated over the heavily militarised frontier shortly after midnight, around 60km north of Seoul.

As well as messages condemning the North's ruling Kim dynasty, the packages contained US$1 bills, small radios and DVDs, group leader Lee Min Bok told AFP. "We staged a quiet operation today because excessive publicity is not good for our humanitarian mission to help our North Korean brothers," Mr Lee said.

North Korea says the South's refusal to ban the balloon launches has jeopardised an agreement to resume high-level talks. Two weeks ago, North Korean border guards attempted to shoot down some balloons launched by Lee's group, triggering a brief exchange of heavy machine gun fire across the border.

South Korea has asked activist groups to show restraint at what it is a sensitive time, but insists it is unable to prohibit the launches.

"They are a matter related to the freedom of expression, so we have no legal grounds to control or restrict them," Defence Ministry spokesman Wi Yong Seob told reporters.

The two Koreas had decided earlier this month to restart high-level talks by early November, and South Korea had proposed meeting on Thursday at the border truce village of Panmunjom.

But the North said the refusal to ban the balloon launches had soured the atmosphere and threatened the whole future of the talks agreement.